Mass shooting in the context of "Gang violence"

Mass murder is the violent crime of killing a number of people, typically simultaneously or over a relatively short period of time and in close geographic proximity. A mass murder typically occurs in a single location where one or more persons kill several others. Data suggests that approximately 30% of mass murderers die in the act.

In the United States, Congress defined mass murders as the killing of three or more persons during an event with no "cooling-off period" between the homicides. The Investigative Assistance for Violent Crimes Act of 2012, passed in the aftermath of the Sandy Hook Elementary School shooting, clarified the statutory authority for federal law enforcement agencies, including those in the Departments of Justice and Homeland Security, to assist state law enforcement agencies, and mandated across federal agencies a definition of "mass killing" as three or more killings during an incident.A mass murder may be further classified as a mass shooting or a mass stabbing. Mass murderers differ from spree killers, who kill at two or more locations with almost no time break between murders and are not defined by the number of victims, and serial killers, who kill people over long periods of time.

Anders Behring Breivik (Norwegian pronunciation: [ˈɑ̂nːəʂ ˈbêːrɪŋ ˈbræ̂ɪviːk] ; born 13 February 1979), officially Far Skaldigrimmr Rauskjoldr av Northriki and formerly Fjotolf Hansen , is a Norwegian neo-Nazi terrorist and mass murderer. He perpetrated the 2011 Norway attacks in which he killed 8 people by detonating a van bomb at Regjeringskvartalet in Oslo, and 2 hours later he committed a massacre that killed 69 participants (33 of the victims being under the age of 18) of a Workers' Youth League (AUF) summer camp, in a mass shooting on the island of Utøya.

After Breivik was found psychologically competent to stand trial, his criminal trial was held in 2012. That year, Breivik was found guilty of mass murder, causing a fatal explosion, and terrorism. Breivik was sentenced to the maximum civilian criminal penalty in Norway, which is 21 years' imprisonment through preventive detention, allowing the possibility of one or more extensions for as long as he is deemed a danger to society.

On December 14, 2012, a mass shooting occurred at Sandy Hook Elementary School in Newtown, Connecticut, United States. The perpetrator, 20-year-old Adam Lanza, shot and killed 26 people. The victims were 20 children between six and seven years old, and six adult staff members. Earlier that day, before driving to the school, Lanza fatally shot his mother at their Newtown home. As first responders arrived at the school, Lanza killed himself with a gunshot to the head.

The incident is the deadliest mass shooting in Connecticut history and the deadliest at an elementary school in U.S. history. The shooting prompted renewed debate about gun control in the United States, including proposals to make the background check system universal, and for new federal and state gun legislation banning the sale and manufacture of certain types of semi-automatic firearms and magazines which can hold more than ten rounds of ammunition.

A "soft target" is a person, thing, or location that is easily accessible to the general public and relatively unprotected, making it vulnerable to military strikes, terrorism, car bombs, or crimes such as vehicle-ramming attacks or mass shootings. By contrast, a "hard target" is heavily defended or not accessible to the general public.

An active shooter is the perpetrator of an ongoing mass shooting. The term is primarily used to characterize shooters who are targeting victims indiscriminately and at a large scale, who oftentimes, will either commit suicide or intend to be killed by police. More generally, an active perpetrator of a mass murder may be referred to as an active killer.

The Federal Bureau of Investigation defines an active shooter as "one or more individuals actively engaged in killing or attempting to kill people in a populated area", excluding gun-related incidents that were the result of self-defense, gang or drug violence, residential or domestic disputes, crossfire as a byproduct of another ongoing criminal act, controlled barricade or hostage situations, or actions that appeared not to have put other people in peril. In 2008, the United States Department of Homeland Security defined an active shooter as "an individual actively engaged in killing or attempting to kill people in a confined and populated area; in most cases, active shooters use firearms and there is no pattern or method to their selection of victims."

A murder–suicide is an act where an individual intentionally kills one or more people, before or while also killing themselves. The suicide may be in response to the guilt one feels for the murder, or to avoid potential punishments, such as imprisonment. Some forms of murder also inherently entail suicide; such as suicide attacks, or when the operator of an aircraft with passengers deliberately crashes it.

Many perpetrators of spree killings, such as mass shootings and school shootings, either end their own lives afterwards, or intend to be killed by police. Some cases of religiously motivated mass suicides have also involved murder. All categorization amounts to forming somewhat arbitrary distinctions where relating to intention in the case of psychosis, where the intention(s) is/are more likely than not to be irrational. Ascertaining the legal intention (mens rea) is inapplicable to cases properly categorized as insanity.

On November 19–20, 2022, an anti-LGBTQ–motivated mass shooting occurred at Club Q, a gay bar in Colorado Springs, Colorado, United States. Five people were killed, and twenty-five others were injured, nineteen of them by gunfire. The shooter, 22-year-old Anderson Lee Aldrich, was also injured while being restrained, and was taken to a local hospital. Aldrich was then charged and remanded in custody. On June 26, 2023, Aldrich pleaded guilty to the shooting and state level charges and was officially sentenced to a total of five consecutive life terms plus an additional consecutive 2,211 years, all without the possibility of parole. On January 16, 2024, Aldrich was additionally charged with 50 federal hate crimes in connection with the shooting. On June 18, 2024, Aldrich pleaded guilty to the federal charges and was sentenced to 55 concurrent life sentences without parole, plus a consecutive 190 years.

Mass shooting contagion theory is the studied nature and effect of media coverage of mass shootings and the potential increase of mimicked events. Academic study of this theory has grown in recent years due to the nature of mass shooting events, frequency of references to previous rampage shooters as inspiration and the acquisition of fame using violence, particularly in the United States. The Columbine High School massacre is cited as being the first shooting to receive nationwide 24/7 publicity, giving both shooters near instant widespread infamy, and thus often is claimed by researchers as being a source of inspiration for would be copycat mass shooters. As of 2025, the fixation of social media has led individuals, specifically men, to express their beliefs even if deemed controversial or unconventional. As these social networks have provided friendly spaces, these forums have also created and harbored toxic communities that align with bigoted beliefs that range across the spectrum of hateful ideologies.