Report: Vast Majority of ‘Mass Attackers’ Exhibit Concerning Behavior Prior to Incident

More than three-quarters of the individuals who committed “mass attacks” exhibited concerning behaviors or shared alarming communications before carrying them out.

That’s the finding of a new U.S. Secret Service report released Wednesday. The agency’s National Threat Assessment Center (NTAC) analyzed 173 mass attacks between 2016 and 2020—incidents in which three or more people, not including the attacker, were harmed in public or semi-public places—to identify commonalities between the incidents that might be used to help prevent future attacks. The report found that nearly two-thirds of attackers during the study period had a history of making violent threats, and 64 percent had a history of criminal charges or arrests.

The report arrives on the heels of two separate mass killings in California that claimed the lives of 18 people in three days. The findings reveal that in most cases, attackers are on the radar of other community members or law enforcement. It suggests that more can be done to identify potential threats and stop future attacks.