Mass murder is the killing of multiple people at the same time in the same general geographic location. A United States federal law passed in 2012, for example, defines mass murder as the unlawful killing of three or more persons during a single, sustained incident. The U.S. Federal Bureau of Investigation (FBI) and some scholars have sometimes defined mass murder as involving four or more victims. Mass murder is different from serial killing or spree killing. Serial killing occurs when the same person kills two or more people over a period of time. Spree killing involves the killing of multiple people in a short time at multiple locations.
Mass murders occur throughout the world. However, countries differ in the way they compile statistics on mass murders. Some governments and agencies track the number of shootings, for example, but not the number of deaths caused by other means, such as knife attacks or strangulations. Others may track public mass murders—especially public mass shootings—but not private mass murders, which generally receive limited media attention. In the United States, for example, the majority of mass murders are private or domestic—that is, the killers are either family members or acquaintances of the victims. Most of these murders are committed by either a man against his wife and children or a woman against her husband and children.
Other mass murders are carried out by a stranger. They usually occur in such public places as the workplace, a movie theater, nightclub, school, mall, or airport. In public mass murders, the victims are most often strangers to the offender. Public mass murders also usually have higher numbers of victims than domestic mass murders.
A small number of mass murderers surrender to or are captured by the authorities. However, mass murderers are more likely to be killed by police or to commit suicide.
There are many motivations for carrying out mass murders, including revenge, power, financial reasons, hate, and in some cases, mental illness. Beginning in the early 2000’s, the number of mass murders motivated by religious ideology (set of opinions) increased. Some of these mass murderers had become radicalized through self-indoctrination or by being recruited by an extremist group. Most of these groups were based on radical militant Islamic ideology. Radicalization is a process through which an individual or group adopts an extreme political, religious, or social philosophy.
