Mass Attacks – Broadly Reviewed

Mass stabbings don’t get as much media attention as mass shootings.

Likewise for mass burnings, drownings or hit-and-runs.

Since guns are the weapon in 73% of mass attacks, understanding mass attacks of all types might be key to preventing mass shootings. The federal government has studied this.


  • Non-gun mass attackers are not different than gun mass attackers.
  • Changes in behavior precede stressors, the latter triggering attacks.
  • The mental health community is letting at-risk people fail.

Mass public attack stats

The National Threat Assessment Center (NTAC), oddly a function of the Secret Service, cataloged five years of mass public attacks 1, which they define as when three or more people (not including perpetrators) were harmed in public or semi-public places.

Like the Violence Project’s work on mass public shootings, NTAC looked deeply into the perpetrators’ lives, motives, modus operandi and more. It is important research for two reasons: motives of mass attackers mirror mass public shooters, and we have basic prescriptions for identifying potential perps without focusing on just gun perps. This is akin to saying we want to understand muggers regardless of whether they use a knife or a gun to mug you.

Warning signs

The similarities between mass public shooters (MPS) and all mass attackers is consistent. Yes, because 73% of mass attacks are MPS, the overall stat is polluted. But non-gun mass attackers share the same traits, so understanding attackers as a group, regardless of weapon use, adds clarity.

Most important are the warning signs – how to spot a mass murderer before they start stabbing, shooting, or torching. Warning signs fall into two categories: long-term traits (i.e., mental health) and near-event issues (i.e., major life stressors). The former may often be the foundation for the latter (i.e., long-term alcoholism followed by getting fired).

Let’s start with the triggers (near-event issues) that are highly visible warning signs, then list instances where intervention might mute the effects of triggering events.

Near-event triggers

Three factors arise: general behavior changes, concerning behaviors, and severe stressors.

Behavioral changes: Nearly half (46%) of perpetrators (perps) showed behavioral changes; and of those, 65% showed changes within a year of the attack. Of those with behavioral changes, a full 68% showed signs of mental health issues, well above general behavior changes (24%) and uncharacteristic actions (17%). The key is not necessarily that they display threatening behaviors, but that their “new” behaviors have no obvious source.

Concerning behaviors: Interestingly, a higher percentage (76%) of perps displayed behaviors that concerned people who knew them. A full 57% of that group reported their concerns (though we have no data on the number of similar reports that stopped a potential perp). Critical, though, is that 64% of all perps showed behaviors that “should have been met with an immediate response” because they were “objectively concerning or prohibited,” including threats, harassment and violence.

Common stressors that trigger perpetrators of mass attacks

Common stressors that trigger perpetrators of mass attacks

Stressors: These budding behavioral concerns lay groundwork for when the perp encounters a significant stressor, of which 93% or perps do, 77% within a year of their attack. As you can see from the chart, perps often have multiple stressors, which is understandable. If, for example, a perp has substance abuse issues, they can cause both family and employment troubles. Of perps who had significant stressors, 49% had them within 30 days of their attack.

These near-event triggers are perhaps the most important thing people should watch for, as they are signs that a tragedy might soon come to pass. But like a healthy lifestyle, prevention is preferable. So, let’s look at the long-term conditions that help lay a foundation for mass attacks.

Long-term traits

Criminality: That 64% of perps dabbled in crime is unsurprising. People with one bad behavior often have more bad behaviors (i.e., the ex-con drunk who picks fights in bars over drug deals gone bad). An accumulation of negative life events from bad behavior might instigate mental health and/or anti-social reactions. Hence, being a crook might be a stepping stone for being a mass murderer.

Substance abuse: About 34% of perps had drug and booze problems, and 12% were drunk, high or tripping during their attack. There is some likely overlap here with mental health, given that 24% of mass public shooters took psychiatric medications and may well have abused those. Which brings us to…

Mental health conditions of mass attack perpetrators

Mental health conditions of mass attack perpetrators

Mental health: A minimum of 34% of perps had mental health issues (we say minimum because some perps may have serious, yet undiagnosed, mental health problems). That 28% are psychotic amplifies what we have noted before, that deinstitutionalization strongly correlates with mass public shootings. When 20% of perps are paranoid and 13% are outright hallucinating, then our mental health system is letting some dangerous folks fall through cracks.

Social isolation: When one detaches from reality (drugs, booze, mental health issues) they can isolate from society (see the Isla Vista spree shooter’s manifesto for a detailed account about how violent video games facilitated his social isolation). As least 29% of perps were identified as “withdrawn, loners, or anti-social.”

“Where” is often “why”

At least 47% of attackers had some affiliation with the location of their assault. Given that significant stressors and grievances trigger attacks, it is understandable why attackers target specific locations (the remaining 53% may have some unknown affiliation, at least in the attacker’s mind). For MPSs, we have any number of instances where this is well documented.

Of concern is that 68% of perps were not targeting specific people. Given that more than half of them have grievances, the randomness of their victims indicates an uncorked rage at the location of their perceived grievances.

All of this leads to perps…

Planning mass attacks

“Only” 31% of perps planned their attacks (that 69% did not demonstrates the “uncorked rage” theory).

Most frequently (by a hair) they planned the venue (studied entry points, security, etc.). After that, they researched weapons.

We know from the sundry MPS databases that well-planned attacks achieve the highest body counts. Someone who displays outsized interest in location minutiae, or having never shown interest in weapons before is suddenly web surfing “flame throwers” and “drum magazines,” might have flipped their grievance switch and be in planning mode for an attack.

For guns, about 23% of attackers acquired them illegally, which disagrees with the longer running Violence Project Database that says about 13% of perps obtains guns illegally. However, the Violence Project database covers 56 years, and this USSS study only a recent five years. Yet, there does not appear to be an increasing frequency of illegally obtained guns in mass attacks over time.

The endings before we end

Though it would be better to have no stressed-out attackers murdering masses, the “good” news is that they generally save us the effort of arresting and imprisoning them.

How mass attacks are ended

How mass attacks are ended

Of passing note is that in 10% of the cases, it was plain folk like you who stopped the carnage. Keep up the good work!


  1. Mass Attacks in Public Spaces: 2016-2020

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