Understanding Active Shooter Events: What the Data Really Tell Us

For most people, when you hear the phrase “active shooter event,” it immediately triggers something visceral. These are terrifying, headline-dominating events that seem to happen with unsettling frequency. But while media coverage often jumps straight to debates about guns, mental illness, or video games, the real story is much more complicated.

Over the past decade, my colleagues and I have conducted two large research studies on active shooter events (ASEs), one in 2015 and a follow-up in 2024, to better understand who commits these acts, what circumstances surround them, and how they’ve changed over time. What we found both confirms some popular assumptions and completely upends others.

How We Got Here

When I was growing up, mass shootings were rare. If one occurred, it was national news for months. The 1966 University of Texas Tower shooting, where Charles Whitman killed 14 people, was an event that defined a generation. By contrast, today, we hear about multiple shootings in a single week. The collective response has shifted from shock to exhaustion.

So we began asking: what changed? Are the perpetrators different? Are the motivations new? Or are we just witnessing more of what has always been there?

Our first study in 2015 took an archival, retrospective approach. We reviewed 88 active shooter events in the United States between 1966 and 2013, analyzing 92 perpetrators. This wasn’t experimental work, we weren’t manipulating variables or running control groups. Instead, we mined decades of data from law enforcement, court documents, and news archives to identify common threads. In 2024, we revisited the question. Using updated data from the Violence Project and USA Today’s mass-killing database, we analyzed 56 more recent events, covering 2015 through 2023. Together, the two studies represent nearly 60 years of American mass-shooting history.

What Counts as an Active Shooter Event?

Before diving into the findings, it’s crucial to define what we mean by an active shooter event. The term itself only entered public use in the early 2000s through law enforcement training manuals (U.S. Department of Homeland Security, 2013). It refers to an individual (or individuals) actively engaged in killing or attempting to kill people in a confined or populated area, often with unrestricted access to additional victims.

These are not robberies gone wrong or gang-related shootings. They’re not terrorist acts with political motives or family annihilation cases. What distinguishes an ASE from other forms of gun-violence is that it involves indiscriminate victims, people who just happen to be in the wrong place at the wrong time.

How Common Are They, Really?

When we compiled data across both studies, we found 144 unique ASEs involving 148 perpetrators between 1966 and 2023. Every year since 1986 has seen at least one such event, but the rate has exploded since 2015. From 1966 to 2014, the United States averaged fewer than two ASEs a year. Since 2015, that average has jumped to about six annually (Gamache et al., 2024).

In total, these incidents have claimed 745 lives and wounded another 850 people. The average event results in around nine fatalities and eleven injuries, numbers that have held remarkably steady over time. So while these attacks are more frequent, they’re not necessarily more deadly on a per-event basis.

The Typical Event

Most active shooter incidents are shockingly short. Over half end within ten minutes, and many conclude in less than five. Some last only a few minutes, the amount of time it takes to make a cup of coffee.

As for weaponry, the stereotype of the “assault rifle”-wielding shooter is only partially accurate. About 70% of shooters used handguns; 36% used semi-automatic long rifles; and only about 16% used true assault-style rifles [with the operational definition of “assault-rifle” that we utilized] (Gamache et al., 2024). In fact, the majority of these weapons were legally owned or easily accessible within the home.

Roughly a third of events occur in schools, once the dominant setting for these tragedies, though that number has dropped in recent years. Others happen in workplaces, public spaces, or government facilities.

The way these incidents end is equally telling. Across both studies, about 40–45% of shooters die by suicide during or immediately after the event. Another third are killed or subdued by police. Only a small minority are stopped by victims or bystanders.

Who Are the Shooters?

The short answer: overwhelmingly men. About 97% of perpetrators in our combined dataset were male. Most were white (roughly 69%), single (78%), and had easy access to firearms (86%).

But beyond those demographics, there’s no single “profile.” Shooters ranged from teenagers to men in their 50s. Some were highly educated; others were not. Some had stable employment; others had histories of instability. The search for a reliable psychological or behavioral “type” has frustrated law enforcement and psychologists for decades, and for good reason as these individuals vary so wildly in their demographic characteristics and motivations.

Still, certain trends stand out. Many perpetrators had histories of behavioral issues: anger problems, aggression, interpersonal conflict, or disciplinary trouble at work or school. More than half displayed concerning behaviors before the attack (Gamache et al., 2015). About one-third had past violent behavior, whether or not it resulted in criminal charges.

When it comes to mental illness, the picture is far more nuanced than public debate suggests. Around 22% had a history of psychological disorders, and about 28% had sought mental health treatment at some point. That’s meaningful, but it also means that roughly three-quarters did not have a documented mental illness.

What was more common were psychological stressors: personal crises, feelings of failure, relationship loss, or suicidal ideation. About 40% were openly suicidal at the time of the event, either seeking “suicide by cop” or expressing a desire to die.

The Myth of the “Dangerous Loner”

Popular narratives often depict mass shooters as isolated, mentally ill “loners.” While some fit that description, many do not. Prior research by the U.S. Secret Service and the Department of Education (Vossekuil et al., 2002) showed that most school shooters were not socially isolated; two-thirds were described by peers as having friends. Our data echo that finding: these individuals are far more heterogeneous than media portrayals suggest.

Motivation and Ideology

Trying to pin down motivation is like trying to solve a puzzle with missing pieces. For many shooters, motives remain unclear. In some cases, ideological extremism (racist, misogynistic, or religious) played a major role. About one-fifth of perpetrators in our 2024 study embraced hateful or extremist beliefs, often framing their actions as “revenge” or “justice” for perceived wrongs.

Others seemed obsessed with previous mass shootings, viewing them with fascination or admiration. Roughly a third demonstrated this kind of fixation. This echoes prior research on the “media contagion effect,” where widespread coverage of mass violence can inspire imitation (Towers et al., 2015).

Schools, Workplaces, and Shifting Settings

One of the most striking findings in our updated study was the shift in location. In our 2015 data, nearly half of active shooter events occurred in schools. By contrast, in the 2015–2023 dataset, that number dropped to about 18% (Gamache et al., 2024). This doesn’t mean schools are safer per se, only that the violence has spread to a wider variety of settings. Some events now occur in places once considered “neutral zones”: churches, concerts, grocery stores, medical offices. In other words, there’s no longer a single archetype of where mass shootings “happen.”

Guns, Policy, and Reality

A predictable theme in public discourse after each tragedy is the call to “keep guns out of the hands of the mentally ill.” The data complicate that narrative. As I often tell students: that’s a political translation of “Let’s talk about mental illness instead of guns.”

Our research found that the majority of shooters obtained their weapons legally. Federal background checks exist, but roughly half of U.S. states allow individuals with valid firearm permits to bypass the National Instant Criminal Background Check System (Bureau of Alcohol, Tobacco, Firearms and Explosives, 2023). Even with systems like the Brady Act in place, loopholes remain. So while firearm regulation is a political flashpoint, our findings suggest that accessibility, not necessarily legality, is the issue. When someone is suicidal or angry, and has access to guns, the barrier to catastrophic violence is dangerously low.

What About Mental Illness?

It’s worth repeating: mental illness alone does not predict violent behavior. Most individuals with mental illness are not violent, and most violent individuals are not mentally ill in a medical sense (APA, 2013). That said, untreated psychological distress, especially when combined with social isolation, anger, and easy access to weapons, can be a dangerous mix. The data show that around a quarter of shooters experienced psychosis, delusional thinking, or hallucinations prior to their attacks (Gamache et al., 2024). But many more simply experienced profound hopelessness, anger, or perceived grievance. These aren’t necessarily psychiatric disorders, they’re emotional states that can escalate when unaddressed.

Why Understanding This Matters

When we talk about “active shooter profiles,” we risk falling into a trap: assuming we can predict who will commit mass violence. But our research, and decades of studies before it, show that no consistent profile exists. That doesn’t mean we’re powerless. It means we need to shift focus, from prediction to prevention.

Early behavioral intervention, supportive school and workplace environments, and destigmatizing help-seeking can all reduce risk. Public health frameworks that treat gun violence as a social and psychological issue, not just a criminal one, offer promise. And perhaps most importantly, we must resist the urge to normalize these events. The fact that we no longer hold national vigils for each tragedy doesn’t make them less tragic. It means we’ve grown weary. But data, and compassion, demand that we stay engaged.

The Takeaway

Our research shows that active shooter events are increasing in frequency, not necessarily in lethality, and that perpetrators are more diverse than stereotypes suggest. These acts are less about mental illness and more about access, opportunity, and personal crisis. No single policy or diagnosis will solve this. What we need is nuanced understanding; acknowledging the complex web of psychological, social, and structural factors that make such violence possible.

Because behind every data point is a life lost, a family shattered, and a community forever changed.

AMENDMENT- 12/29/25

The above post was based upon a talk that Dr. Zaitchik and I gave on October 29, 2025 as part of the Roger Williams Psychology Colloquium Series. I spent several weeks prepping the post and then it largely was shelved while I dove into end-of-semester grading. While I was doing so, two mass-shooting events occurred. One at Brown University in Providence, Rhode Island, and the other at Bondi Beach, in Sydney Australia, both on December 13, 2025. Like all of these kinds of events, these were horrific with multiple fatalities. The Brown shooting was the first event of this kind in Rhode Island and one of the first in New England. The Bondi Beach shooting was the first of its kind in Australia in almost 30 years.

Researching these kinds of events has been fraying to say the least throughout the last ten years, but the Brown shooting is particularly jarring because of how close we are to it. Dr. Zaitchik is an alum of Brown, and I lived next to the open campus during graduate school. It’s Rhode Island, so many people have some connection to Brown or the East Side of Providence. All the more surreal, several news outlets found our research on active shooting events and reached out to interview us. Our interviews were on the evening news and published in the Boston Globe. While an interesting experience, this was certainly not the circumstances I’d like to be interviewed under.   

References

American Psychological Association. (2013). Gun violence: Prediction, prevention, and policy. APA Task Force Report.

Bureau of Alcohol, Tobacco, Firearms and Explosives. (2023). Federal firearms regulations reference guide.

Gamache, K., Platania, J., & Zaitchik, M. (2015). An examination of the individual and contextual characteristics associated with active shooter events. Open Access Journal of Forensic Psychology, 7, 1–20. https://docs.rwu.edu/fcas_fp/203/

Gamache, K., Zaitchik, M. C., Platania, J., Coslovi, C., & Pontbriand, W. (2024). A second look at active shooter events: Expanding our understanding of key factors. Journal of Psychology and Behavioral Science, 12, 17–27. https://docs.rwu.edu/fcas_fp/1112/

Towers, S., Gomez-Leyva, J., Khan, M., Mubayi, A., & Castillo-Chavez, C. (2015). Contagion in mass killings and school shootings. PLOS ONE, 10(7), e0117259.

U.S. Department of Homeland Security. (2013). Active shooter: How to respond.

Vossekuil, B., Fein, R. A., Reddy, M., Borum, R., & Modzeleski, W. (2002). The final report and findings of the safe school initiative. U.S. Secret Service and U.S. Department of Education.