Mass shootings are incidents involving multiple victims of firearm-related violence. The precise inclusion criteria are disputed, and there is no broadly accepted definition. One definition is an act of public firearm violence—excluding gang killings, domestic violence, or terrorist acts sponsored by an organization—in which a shooter kills at least four victims. Using this definition, one study found that nearly one-third of the world's public mass shootings between 1966 and 2012 (90 of 292 incidents) occurred in the United States.Using a similar definition, The Washington Post records 163 mass shootings in the United States between 1967 and June 2019.
Gun Violence Archive, frequently cited by the press, defines a mass shooting as firearm violence resulting in at least four people being shot at roughly the same time and location, excluding the perpetrator. Using this definition, there have been 2,128 mass shootings since 2013, roughly .62 per day.
The United States has had more mass shootings than any other country. Shooters generally either die by suicide afterward, or are restrained or killed by law enforcement officers. Mass shootings accounted for under 0.2% of homicides in the U.S. between 2000 and 2016.