The term mass murder refers to when a murder of four people or more happens by the same person of group at the same time. Usually the murders happen at the same time or over a relatively short period of time. The FBI defines mass murder as the killing of many people without any cooling off period. By comparison a serial killer has a cooling off period between murders. Murder can be done by a person, a terrorist group, a government or police. Mass murderers commit their crime for many reasons. Examples of why they do it include, getting bullied, mental disorder or inceldom. In many cases, the killer commits suicide or is killed by police.
The University of Texas massacre in August 1966, the 1999 Columbine High School massacre, the Virginia Tech massacre, the 2012 Aurora shooting and the 2012 Sandy Hook Elementary School shooting are some examples of mass murders that have happened in the United States.
- "Serial Murders". The Federal Bureau of Investigation. Retrieved Feb 4, 2014.
- Lee Mellor, Rampage: Canadian Mass Murder and Spree Killing (Toronto: Dundurn Press, 2013), p. 15
- Nagle, Angela. "The New Man of 4chan." The Baffler 30 (2016): 64-76.
- "School Shooting: 28 dead". The New York Times. Retrieved Feb 4, 2014.