More than 900 people died in mass shootings in the past seven years, and a majority of them were killed by people they knew, says USA Today. The 934 deaths account for less than 1 percent of gun-related homicides, and nearly half involve a suspect slaying his or her family members. USA Today examined FBI records and news accounts to identify 146 mass shootings since 2006 that matched the FBI definition of mass shooting, where four or more people were killed.

A separate analysis of 56 mass shootings since 2009 from a group of mayors promoting gun control reaches similar conclusions. Fifty-seven percent of cases reported by Mayors Against Illegal Guns involved domestic violence. The group, co-founded by New York City Mayor Michael Bloomberg, is made up of more than 850 U.S. mayors.