The longest-running and most extensive data source on mass killings reveals that 2,646 people in the United States have died in 504 events over the past 17 years. The Associated Press/USA TODAY/Northeastern University Mass Killings Database, maintained by James Alan Fox, a Northeastern professor, was made available to the public on Thursday.
It references every mass killing, by all weapons and means, in which four or more people (excluding the offender) were killed within a window of 24 hours. Fox’s database provides a different perspective than other firearm-related sites, including the Gun Violence Archive, which includes shootings with four or more victims, most of whom survive their injuries. Less than 5% of mass shootings in the Gun Violence Archive are mass killings.