Mass shootings are incidents involving several victims of firearm-related violence. The precise inclusion criteria are disputed, and there is no broadly accepted definition.[1][2]
The Gun Violence Archive, a nonprofit research group that tracks shootings and their characteristics in the United States, defines a mass shooting as an incident in which four or more people, excluding the perpetrator(s), are shot in one location at roughly the same time.[3] The Congressional Research Service narrows that definition further, only considering what it defines as "public mass shootings", and only considering victims as those who are killed, excluding any victims who survive.[2]The Washington Post and Mother Jones use similar definitions, with the latter acknowledging that their definition "is a conservative measure of the problem", as many rampages with fewer fatalities occur.[4][5] The crowdsourced Mass Shooting Tracker project uses a definition even looser than the Gun Violence Archive's definition: four people shot in one incident regardless of the circumstances.[6]
Larger documentation of mass shootings in the United States has occurred through independent and scholarly studies such as the Stanford University Mass Shootings in America Data Project.[4][2]
There are varying definitions of a mass shooting. Listed roughly from most broad to most restrictive:
Stanford MSA Data Project: 3+ shot in one incident, at one location, at roughly the same time, excluding organized crime, as well as gang-related and drug-related shootings.[7]
Mass Shooting Tracker: 4+ shot in one incident, at one location, at roughly the same time.[6]
Gun Violence Archive/Vox: 4+ shot in one incident, excluding the perpetrator(s), at one location, at roughly the same time.[3]
Mother Jones: 3+ shot and killed in one incident, excluding the perpetrator(s), at a public place, excluding gang-related killings.[8]
The Washington Post: 4+ shot and killed in one incident, excluding the perpetrator(s), at a public place, excluding gang-related killings.[4]
Congressional Research Service: 4+ shot and killed in one incident, excluding the perpetrator(s), at a public place, excluding gang-related killings, acts carried out that were inspired by criminal profit, and terrorism.[9]
Collier Township shooting: A man entered a women's aerobics class and opened fire, killing three people and injuring nine before committing suicide.[13]
Carthage nursing home shooting: A man attacked the workplace of his estranged wife, killing eight people and wounding two others before being arrested.
A man fatally shot his wife and five children before committing suicide. Before the shooting, he faxed a letter to a local TV station that stated he and his wife were fired from their jobs and intended to kill themselves and their children.[19]
Covina massacre: A man entered his former in-laws' home armed with four handguns and a homemade flamethrower. He killed nine people and injured three before committing suicide.[21]
Knoxville Unitarian Universalist church shooting: A former truck driver opened fired at a church during a church youth performance, killing two and wounding six before being restrained by churchgoers. A manifesto written by the gunman attributed the shooting to hatred of liberals, Democrats, African-Americans, and homosexuals.
A man fatally shot his brother during an argument, before fatally shooting three female witnesses and stabbing five children, two of whom died. One month before the attack, the perpetrator was released from prison after serving 14 years for second-degree murder.[25]
Northern Illinois University shooting: A former graduate student entered a lecture hall and opened fire, killing five people and wounding twenty-one before committing suicide.
Kirkwood City Council shooting: A man opened fire during a public city council meeting, killing six people and injuring one other before being shot and killed by police.[26]
Lane Bryant shooting: Four customers and the stores manager were killed at a clothing store, and a part-time worker was injured in a robbery gone awry.[27]
Crandon, Wisconsin, duplex shooting (2007): An off-duty sheriff's deputy entered a homecoming party at a duplex with a semiautomatic rifle and killed six people and wounded one. He killed himself later that day.
Virginia Tech shooting: A 23-year-old student killed thirty-three students and teachers, and wounded seventeen others. Other people were injured attempting to escape. When police stormed the building he was in, the shooter killed himself.
Trolley Square shooting: A man opened fire in a parking garage and shopping mall and killed five people and injured four others before being killed by police.
A man fatally shot his cousin, girlfriend, and their three children before killing himself. A fourth child who was shot survived. Relatives claimed that he was depressed and acting irrationally in the weeks leading up to the shooting.[32]
West Nickel Mines School shooting: A man took hostages in an Amish schoolhouse, and killed five schoolgirls and injured five others before committing suicide.
Seattle Jewish Federation shooting: The perpetrator forced his way into the building, repeatedly shouting that he was angry at Israel and wanted to make a statement, he killed one and injured six.[36]
South Shore Park shooting: A man shot five people, killing two, after his estranged wife told him that he could not see his daughter. He then fled to Mexico, where he was captured 15 years years after being put on the FBI's most wanted list.
A man fatally shot four of his in-laws at a church before abducting his wife and their three children. He later slew his wife at an apartment complex.[40]
Capitol Hill massacre: A guest returned to a house party armed with a shotgun and a semiautomatic handgun. He shot indiscriminately, killing six people and injuring two, before committing suicide.
Goleta postal facility shootings: A woman killed her neighbor before driving to the mail processing plant, where she shot and killed six people before committing suicide.
Tacoma Mall shooting: A man attempted suicide by cop by opening fire in a shopping mall with an illegal MAK 90 semi-automatic rifle and a pistol. He injured six people and took four hostages before surrendering to a SWAT team.
Wesson family murders: A man convicted of the molestation and murders of his children and nieces shot and killed nine members of his family during a standoff over a child custody dispute.[51]
Serial killer Todd Kohlhepp fatally shot four people at Superbike Motorsports, allegedly as a result of him being laughed at for not knowing how to ride a motorcycle.[52][53]
After robbing a convenience store earlier in the day, a 30-year-old man killed four people and injured two others during a botched robbery at another convenience store. He, along with his girlfriend, proceeded to lead police on a high-speed chase. After crashing his car and fleeing on foot, he fatally shot himself in a backyard. The perpetrator had previously killed a classmate at Murray–Wright High School in 1987.[54]
A 34-year-old man, who was armed with three handguns, kerosene and sword, shot and wounded three at a wine bar in East Village. He took hostages and was then shot and injured by police before being arrested.[58][59]
2003 Ennis shooting: A man opened fire on a group of people outside of a bar, and then engaged in a high speed chase and shootout with law enforcement, he killed one and injured ten including himself.[60]
Los Angeles International Airport shooting: The gunman opened fire at a line of passengers at a ticket counter, he killed two and injured five before being killed by a security officer.[62]
Appalachian School of Law shooting: A former student opened fire after a meeting with a professor in the offices of the dean of students and a professor, killing them and a student and injured three other students before he was subdued by a Marine veteran.[63]
After a fight with a co-worker, a 36-year-old man fatally shot one and wounded six people at the Nu-Wood Decorative Millwork with a shotgun before committing suicide.[64][65]
Santana High School shooting: A 15-year-old student entered a boys bathroom and shot another student then left and began to fire widely, another student was killed and thirteen were injured.[66]
2001 Navistar shooting: A 66-year-old man returned to his former workplace and fatally shot four people and injured four others before committing suicide.[67]
Richard Baumhammers killing spree: A man went on a killing spree and murdered a Jewish woman before setting her house on fire and firing upon a synagogue vandalizing it with swastikas, killed an Indian man who would die from his injuries at a grocery store, shot up another synagogue, killed two at a Chinese restaurant, and an African-American exercising with his White American friend.[71]
Three days after being fired from a car wash for exposing himself to a female customer, Robert Wayne Harris entered his former place of employment and began shooting co-workers, killing five. He also confessed to killing a woman in 1999. Harris was sentenced to death and executed on September 20, 2012.
2000 Wilkinsburg shooting: After having a heated argument with 2 maintenance workers, Ronald Taylor killed one of the maintenance men before later killing two others at Burger King and McDonald's restaurants.
^ abcBjelopera, Jerome (March 18, 2013). "Public Mass Shootings in the United States"(PDF). Congressional Research Service. Archived from the original(PDF) on September 9, 2013. Retrieved August 26, 2018. There is no broadly agreed-to, specific conceptualization of this issue, so this report uses its own definition for public mass shootings.
^Follman, Mark; Aronsen, Gavin; Pan, Deanna (September 20, 2018). "A Guide to Mass Shootings in America". Mother Jones. Archived from the original on May 28, 2019. Retrieved August 26, 2018.
^Bjelopera, Jerome (March 18, 2013). "Public Mass Shootings in the United States"(PDF). Congressional Research Service. Archived from the original(PDF) on September 9, 2013. Retrieved August 26, 2018. There is no broadly agreed-to, specific conceptualization of this issue, so this report uses its own definition for public mass shootings.