Most people arrive at work expecting routine problems: a printer that has declared independence, a meeting that could have been an email, or a coworker reheating fish in the break room. They do not expect violence. Yet workplaces can become settings for intimidation, assault, targeted attacks, and mass casualty incidents.
The Occupational Safety and Health Administration defines workplace violence broadly as acts or threats of physical violence, harassment, intimidation, and other threatening behavior occurring at a worksite. It can involve employees, former employees, customers, patients, visitors, or people connected to workers through personal relationships.
The danger is not merely theoretical. The U.S. Bureau of Labor Statistics recorded 470 workplace homicides in 2024, including 379 deaths caused by shootings. Most workplace violence never becomes a nationally known tragedy, but the cases that do often expose weaknesses in reporting systems, threat assessment, access control, emergency planning, and post-incident care.
The following 10 workplace violence cases are presented respectfully and without unnecessary graphic detail. Their value lies not in sensationalism, but in understanding how ordinary workplaces became scenes of extraordinary lossand what employers can learn from them.
1. The Edmond Post Office Massacre
Edmond, Oklahoma August 20, 1986
On an August morning in 1986, postal employee Patrick Sherrill entered the Edmond Post Office and attacked his coworkers. Fourteen employees were killed and six others were wounded before Sherrill died by suicide. The violence unfolded in approximately 15 minutes.
The scale of the attack shocked the country. It also helped bring national attention to the possibility that unresolved employee grievances, threatening behavior, disciplinary conflict, and access to weapons could combine with devastating consequences.
The tragedy prompted extensive reviews of how the U.S. Postal Service supported employees, communicated during emergencies, responded to trauma, and managed potentially dangerous workplace behavior. Federal investigators also studied the assistance provided to survivors and victims’ families.
Unfortunately, the incident later became associated with a cruel slang expression about postal workers. That phrase reduces real human suffering to a punchline and unfairly stigmatizes hundreds of thousands of employees. The more useful legacy is the recognition that workplace safety must include behavioral threats, not only wet floors and malfunctioning machinery.
2. The Standard Gravure Shooting
Louisville, Kentucky September 14, 1989
Three years after the Edmond tragedy, an employee on disability leave entered the Standard Gravure printing plant in Louisville. He killed eight people, wounded 12 others, and then died by suicide.
Reports indicated that the employee had experienced longstanding conflict and resentment related to work. Coworkers later described previous threatening comments, including statements suggesting that he intended to return and seek revenge. Whether every remark was understood literally at the time is less important than the painful lesson that repeated threats cannot be filed under “probably just venting” and forgotten.
The attack became one of the most widely discussed workplace shootings of its era. Survivors continued to report lasting physical and emotional effects decades later. For many, returning to an industrial building, hearing a loud mechanical noise, or passing an anniversary date could reactivate memories of the event.
This case demonstrated why companies need a structured reporting process. Employees should know exactly where to report threats, who evaluates them, how reports are documented, and what happens next. A hotline nobody trusts is about as useful as an umbrella made of crackers.
3. The Xerox Murders
Honolulu, Hawaii November 2, 1999
In 1999, Xerox service technician Byran Uyesugi entered a company facility in Honolulu and killed seven coworkers, including his supervisor. He later surrendered following a police standoff and was convicted of first-degree murder and attempted murder.
The incident became the deadliest mass killing in Hawaii at the time. Prosecutors said the victims had gathered for a meeting that was expected to address workplace matters involving Uyesugi. Reports also described a history of concerning behavior, conflict with supervisors, and difficulty adapting to proposed changes in his duties.
After the murders, Hawaii cited Xerox over alleged failures involving the enforcement of workplace violence policies. The broader lesson was uncomfortable but important: possessing a written policy does not automatically create safety.
A policy must be communicated, practiced, supported by leadership, and applied consistently. Managers also need training in how to escalate serious behavioral concerns. Without that infrastructure, a beautifully formatted policy can spend years sleeping peacefully inside a binder while employees remain unsure what to do.
4. The Edgewater Technology Shooting
Wakefield, Massachusetts December 26, 2000
On the first workday after Christmas in 2000, Edgewater Technology employee Michael McDermott entered the company’s Wakefield office carrying multiple weapons. Seven coworkers were killed. Police arrested McDermott inside the building, and he was later convicted of murder.
Investigators believed financial pressure played an important role. The company had been legally required to withhold part of McDermott’s wages for unpaid federal taxes. Several victims worked in departments connected to finance, administration, and human resources.
The case illustrates a recurring problem in workplace violence prevention: organizations sometimes treat a dispute as exclusively administrative even when an employee begins showing hostility, fixation, or threatening behavior. Payroll, human resources, security, legal counsel, and management may each hold one piece of the puzzle without anyone seeing the complete picture.
Modern threat assessment teams are intended to solve that problem. They bring together representatives from relevant departments to review facts, distinguish ordinary frustration from escalating danger, document decisions, and coordinate protective action.
5. The Lockheed Martin Plant Shooting
Meridian, Mississippi July 8, 2003
In 2003, assembly worker Douglas Williams opened fire at a Lockheed Martin aircraft parts plant near Meridian. He killed six coworkers, wounded eight others, and then died by suicide.
The attack was especially disturbing because evidence later showed that Williams had made racist statements, threats, and hostile comments toward Black coworkers. Five of the six people killed were Black. Employees told investigators and journalists that troubling conduct had occurred long before the attack.
This was not simply a story about an employee suddenly becoming violent without context. It raised questions about harassment reporting, management response, workplace culture, and whether repeated threats had been handled with sufficient urgency.
Companies cannot separate violence prevention from anti-harassment enforcement. Racist threats, stalking, intimidation, and targeted hostility are not merely interpersonal unpleasantness. They can be indicators of escalating risk and must be documented, investigated, and addressed.
Employees also need protection from retaliation when reporting misconduct. A worker who believes speaking up will damage a career may remain silent, leaving management with less information precisely when more information is needed.
6. The Hartford Distributors Shooting
Manchester, Connecticut August 3, 2010
Hartford Distributors driver Omar Thornton attended a disciplinary meeting after the company obtained evidence that he had stolen from the business. He was offered the option to resign or be terminated. Shortly afterward, he attacked coworkers, killing eight and seriously wounding two before dying by suicide.
Thornton claimed that he had experienced racial harassment at the workplace. Company and union representatives disputed aspects of those allegations, and a police investigation reported that it did not substantiate the broader claims. Regardless of the dispute, nothing justified the murders.
The timing of the attack highlights a well-known risk period: termination, suspension, disciplinary action, or another event perceived as a major loss. Most employees who are dismissed never become violent, and termination alone is not a predictor. However, the risk can rise when job loss is combined with threats, fixation, severe instability, stalking, access to weapons, or a history of aggression.
High-risk meetings should therefore be planned thoughtfully. That can include choosing a controlled location, notifying security, limiting access to work areas, recovering credentials, arranging safe transportation, protecting affected employees, and monitoring later communications.
7. The Washington Navy Yard Shooting
Washington, D.C. September 16, 2013
In 2013, government contractor Aaron Alexis entered Building 197 at the Washington Navy Yard and killed 12 people. Multiple others were wounded before law enforcement officers fatally shot him.
Alexis possessed valid credentials that allowed him to enter the secure facility. Investigations later examined his background, security clearance, mental health contacts, and previous interactions with police. The tragedy revealed how fragmented information can prevent organizations from recognizing a developing risk.
One agency may know about an arrest. Another may receive reports of disturbing behavior. A medical provider may hear alarming claims. An employer may notice deteriorating performance. Unless rules and reporting systems allow relevant concerns to reach the right decision-makers, every organization may believe someone else has the full story.
The attack also demonstrated the importance of emergency communication. During a rapidly moving incident, employees need simple instructions, dependable alerts, clear evacuation or shelter options, and accurate accountability procedures. Nobody should be expected to locate a 94-page emergency manual while danger is moving down the hallway.
8. The Henry Pratt Company Shooting
Aurora, Illinois February 15, 2019
In February 2019, an employee at the Henry Pratt Company in Aurora was called to a termination meeting. After being dismissed, he opened fire, killing five employees. Six other people were wounded, including five police officers. The attacker was killed during an exchange of gunfire with responding officers.
One victim was a 21-year-old human resources intern attending his first day at the company. Others included longtime employees, managers, and union representatives. The range of victims underscored how a single high-risk employment action can expose reception staff, human resources personnel, supervisors, witnesses, security employees, and nearby workers.
The attacker had a prior felony conviction that legally prohibited him from possessing a firearm. Authorities later examined how he had obtained and retained the weapon.
For employers, the central lesson is that termination safety cannot rest entirely on the judgment of the manager conducting the meeting. A consistent protocol should consider prior threats, disciplinary history, known grievances, access to facilities, domestic concerns, unusual communications, and the employee’s response to previous setbacks.
9. The Virginia Beach Municipal Center Shooting
Virginia Beach, Virginia May 31, 2019
On May 31, 2019, a city engineer entered Building 2 of the Virginia Beach Municipal Center and killed 12 people. Eleven victims were city employees, while one was a contractor visiting the building. Five other people were wounded.
The attacker had submitted his resignation earlier that day. Investigators conducted an extensive review but did not establish a simple motive that explained the crime. That finding matters because public discussion often searches for one obvious triggera bad evaluation, a dispute, a breakup, or a termination. Real threat cases are rarely that tidy.
The city commissioned criminal and independent reviews examining security, communications, emergency medical response, building access, employee training, and recovery. Later recommendations included stronger emergency planning, additional responder preparation, bleeding-control training, and improved victim support.
The absence of a clear motive does not make prevention meaningless. Threat assessment is not fortune-telling. Its purpose is to identify concerning behavior, evaluate risk using available evidence, protect potential targets, and interrupt movement toward violence whenever possible.
10. The Santa Clara Valley Transportation Authority Shooting
San Jose, California May 26, 2021
In May 2021, a Santa Clara Valley Transportation Authority employee attacked coworkers at the Guadalupe light-rail yard in San Jose. Nine employees were killed before the attacker died by suicide. The incident became the deadliest mass shooting in the San Francisco Bay Area.
The violence deeply affected a workforce responsible for keeping a major public transportation system operating. Service was disrupted, employees required extensive support, and the agency later considered the emotional impact of continuing to use parts of the facility where the attack occurred.
The case demonstrates that recovery is not complete when police vehicles leave. Survivors may still need to enter the same gate, hear the same machinery, wear the same uniform, or perform work once shared with murdered colleagues.
VTA developed employee support programs and eventually pursued the removal of a building closely associated with the attack. Those decisions recognized that physical environments can become trauma reminders. Recovery planning must therefore address facilities, schedules, staffing, memorials, counseling, compensation, communication, and long-term trust.
Patterns Across These Workplace Violence Cases
These incidents occurred in different decades and industries, but several patterns appear repeatedly.
Threats were sometimes visible before the attack
Some attackers had previously made threatening statements, displayed hostility, targeted coworkers, or developed intense grievances. Warning behavior does not mean violence is inevitable, but it creates an opportunity for assessment and intervention.
Employment actions sometimes became crisis points
Termination, discipline, reassignment, financial withholding, and conflict with supervisors appeared in several cases. These events should not automatically be treated as dangerous, but employers should evaluate the surrounding behavior and circumstances.
Information was often scattered
Human resources might know about discipline while coworkers know about threats and security knows about access problems. A multidisciplinary threat assessment process helps connect those dots without turning the workplace into a suspicious reality show.
Written policies were not always enough
Employees need practical training, trusted reporting channels, emergency drills, accessible exits, reliable alerts, and leaders who respond consistently. A policy nobody understands is paperwork, not prevention.
Recovery lasted for years
Survivors, families, coworkers, dispatchers, medical personnel, and first responders frequently carried the effects long after public attention faded. Recovery requires patience, privacy, financial support, trauma-informed leadership, and access to qualified mental health care.
How Employers Can Strengthen Workplace Violence Prevention
An effective workplace violence prevention program should begin with a written policy covering threats, harassment, intimidation, stalking, domestic violence spillover, physical assaults, and weapons violations. Employees must know how to report urgent and non-urgent concerns without fear of retaliation.
Organizations should establish a trained threat assessment team that can review concerning behavior from multiple perspectives. Depending on the organization, the team may include human resources, security, legal counsel, operations leaders, occupational health specialists, mental health consultants, and law enforcement partners.
Employers should also assess physical security. Important considerations include visitor management, badge deactivation, locks, lighting, cameras, alarm systems, escape routes, secure rooms, reception-area design, and access to isolated work locations.
Training should be realistic without becoming theatrical. Employees need to recognize warning behavior, report concerns, respond to alerts, evacuate when possible, shelter when necessary, contact emergency services, and provide basic aid when it is safe to do so.
Finally, organizations must plan for the aftermath. That includes family assistance, payroll continuity, leave policies, memorial decisions, media communication, counseling, building restoration, legal obligations, and support for employees who cannot immediately return to the same environment.
Conclusion
The most frightening aspect of these workplace violence cases is not that every incident followed the same formula. They did not. Some involved termination, some involved longstanding grievances, some included documented threats, and others left investigators without a clear motive.
The shared lesson is that workplace violence prevention cannot be assigned to one department and forgotten. It requires cooperation among employees, supervisors, human resources, security professionals, executives, health specialists, and public safety agencies.
No program can promise perfect prediction. Human behavior does not arrive with a convenient warning label. Nevertheless, employers can reduce risk by taking threats seriously, sharing relevant information responsibly, planning difficult employment actions, maintaining secure facilities, practicing emergency procedures, and supporting people after traumatic events.
A safe workplace is not one where nobody ever becomes angry. It is one where concerning behavior is reported early, evaluated professionally, and managed before anger develops into action.
Experiences and Lessons From the Aftermath of Workplace Violence
The experience of workplace violence does not end when an attacker is stopped. For survivors and coworkers, the aftermath can begin with confusion rather than relief. Employees may not know who is safe, where injured colleagues were taken, whether family members have been notified, or when they will be permitted to leave. Phones ring continuously. Rumors travel faster than official updates. Ordinary workplace communication systems, designed for schedule changes and birthday reminders, suddenly have to carry life-changing information.
Many survivors describe returning to work as one of the hardest stages of recovery. A familiar hallway can feel threatening. A slammed door may sound like gunfire. An unexpected announcement may trigger panic. Employees who were absent during an attack can also experience guilt because they survived through coincidence: a sick day, a delayed commute, or an appointment that kept them away.
Managers face a different but equally difficult experience. They must support grieving employees while grieving themselves. They may be asked to discuss staffing, payroll, leave, security, media inquiries, memorial services, and business continuity within hours of losing friends and colleagues. Leaders who pretend to be emotionally untouched can unintentionally signal that everyone else should hide their reactions too.
The most helpful leadership is usually calm, honest, and practical. Employees need clear information about what is known, what remains unknown, when the next update will arrive, and where they can obtain assistance. Promising certainty where none exists damages trust. Saying “we do not know yet, but we will update you at 3 p.m.” is often more reassuring than a polished paragraph containing no useful information.
Organizations also learn that counseling cannot be treated as a one-day service. Some employees seek help immediately. Others experience symptoms weeks or months later, especially during funerals, legal proceedings, anniversaries, or the reopening of a facility. Support should remain available and should include options outside the employer’s normal assistance program when specialized trauma care is necessary.
Another common experience is disagreement over memorials and recovery decisions. Some people want permanent reminders of those who died. Others do not want to pass a memorial every morning. Some employees wish to return quickly because routine feels stabilizing, while others cannot imagine entering the building again. There is no single emotionally correct response.
Employers should therefore provide choices whenever operations allow. Flexible schedules, temporary work locations, remote assignments, additional leave, modified entrances, private counseling, and voluntary remembrance activities can help employees recover without forcing everyone through the same process.
These cases also teach workers an important lesson about reporting. Employees sometimes hesitate because they do not want to overreact, damage a coworker’s career, or become known as the office alarm bell. A strong system makes clear that reporting concerning behavior is not the same as declaring someone guilty. It simply gives trained professionals an opportunity to evaluate the situation.
The central experience shared across many tragedies is the realization that workplace culture matters before, during, and after a crisis. Employees are more likely to report danger when leaders listen to ordinary concerns. They are more likely to follow emergency instructions when training has been practical. They are more likely to recover when support continues after headlines disappear.
Prevention begins long before an emergency alarm. It begins with everyday trust, respectful management, consistent enforcement, and the belief that safety concerns deserve attentioneven when addressing them is inconvenient.
SEO Information
Editorial note: This article discusses real acts of violence for educational and workplace-safety purposes. It avoids graphic descriptions, does not glorify offenders, and emphasizes prevention, preparedness, victim dignity, and long-term recovery.
