According to the U.S. Secret Service National Threat Assessment Center’s report on Mass Attacks in Public Spaces, there were 28 mass attacks (during which three or more persons were harmed) carried out in public places within the U.S. in 2017. The attacks resulted in losses of 147 lives, with nearly 700 others injured.

Nearly half of the attacks were motivated by a personal grievance related to a workplace, domestic or other issue, and over half of attackers had histories of criminal charges, mental health symptoms and/or illicit substance use or abuse. All had at least one significant stressor over the last five years, and more than half had indications of financial instability in that timeframe. Over three-quarters made concerning communications and/or elicited concern from others prior to the attacks. On average, the report says, those who elicited concern caused more harm than those who did not.

Thirty-two percent of attacks took place in open spaces, such as sidewalks or outdoor events. Nearly half of the attacks (which were carried out at 31 different sites) occurred at a business. Most of the attacks were carried out with a firearm (82 percent), vehicles (11 percent) and knives (7 percent).

All of the attackers were male, with an average age of 37 years old.