Mass shootings are incidents involving multiple victims of firearm-related violence.
An act of public firearm violence, in which a shooter kills at least four victims.
Nearly one-third of the world’s public mass shootings between 1966 and 2012 occurred in the United States.
The Washington Post recorded 163 mass shootings in the United States between 1967 and June 2019.
Mass shootings account for less than 1% of homicides in the US, but their effect on public consciousness is much more significant.
The United States has had more mass shootings than any other country.
Mass shooters generally either die by suicide afterward, or are restrained or killed by law enforcement officers.
Mass shootings accounted for under 0.2% of homicides in the U.S. between 2000 and 2016.
Some define mass shooting as an incident where four or more people are shot in a single shooting spree, including the perpetrator or police shootings of civilians around the perpetrator, and irrespective of the motive of the perpetrator or the location of the murders.
In nearly all mass shootings the shooter is an adult man who acted alone.
Thirty-two percent of mass shootings end with the perpetrator dying by suicide, and another high percentage are killed by responding law enforcement.
Mass shootings tend to occur in clusters.
The proportion of mass shooters in the United States who are white is slightly less than the overall proportion of white people in the general population of the US.
Asians are overrepresented in mass shootings, having perpetrated 6.06% of attacks despite being 5.7% of the population.
The proportion of male mass shooters is considerably larger than the proportion of males in the general population.
White men comprise nearly 50 percent of all mass shooters in the US.
Mass shootings of family members are usually carried out by white, middle-aged males.
Mass shootings of family members is most common.
Felony-related mass shootings, connected with a previous crime, tend to be committed by young Black or Hispanic males with extensive criminal records, typically against people of the same ethnic group.
Public mass shootings of persons unrelated to the shooter, and for a reason not connected with a previous crime is the rarest but most publicized are committed by men whose racial distribution closely matches that of the nation as a whole.
Older findings of a sociodemographic network’s data found that 96.6 percent were male, 68.9 percent had never married or were divorced or separated from their spouse and only 27.7 percent were reported to have children.
Lone-actor mass shooting attacks are rarely sudden or impulsive, that a wide range of activities and experiences preceded lone actors attacks, that many but not all lone-actors are socially isolated, and that lone-actors regularly engage in a detectable and observable range of activities with a wider pressure group, social movement, or terrorist organization.
A sizable subset of mass shooters take preparations to maximize their chances of death by cop or suicide.
Studies show the perpetrator of mass shootings is female in only 4% of cases.
Only 1% of cases is there more than one perpetrator.
The US has the highest per-capita gun ownership in the world with 120.5 firearms per 100 people; the second highest is Yemen with 52.8 firearms per 100 people.
The state prevalence of firearm ownership is significantly associated with the state incidence of mass killings with firearms, school shootings, and mass shootings.
States with more permissive gun laws and greater gun ownership had higher rates of mass shootings, and a growing divide appears exists between restrictive and permissive states.
A 10% increase in state gun ownership was associated with a significant 35.1% higher rate of mass shootings.
Laws requiring permits to purchase a gun are associated with a lower incidence of mass public shootings, and bans on large capacity magazines are associated with fewer fatalities and nonfatal injuries when such events do occur.
A study found large-capacity magazine bans were associated with approximately 38% fewer fatalities and 77% fewer nonfatal injuries when a mass shooting occurred.
The American Psychiatric Association has endorsed assault weapons bans, high-capacity magazine bans, and universal background checks as a way to curb gun violence in the U.S.
It is estimated that roughly one-third of acts of mass violence—defined as crimes in which four or more people were killed—were committed by people with a serious mental illness.
People with a serious mental illness are responsible for less than 4% of all the violent acts committed in the United States.
The overwhelming majority of people with mental illness are not violent and are far more likely to be victims of violent crime than perpetrators of violence.
The American Psychiatric Association has endorsed red flag laws to remove firearm access from people at high risk of committing acts of violence.
Mass shooters in the United States are more likely to have legal histories, to engage in recreational drug use or alcohol abuse, and to display non-psychotic psychiatric or neurologic symptoms.
Mental illness is not a very specific predictor of violence of any type, let alone targeted violence.
Having a formal mental health disorder diagnosis is more predictive of being a victim of violence rather than a perpetrator.
In a published survey of 172 mass shooters coded on 166 life history variables found that symptoms of psychosis played no role in 69 percent of mass shootings.
In a report analyzing 41 school shootings in the United States, 78 percent of the shooters surveyed had histories of suicidal ideation or attempted suicide.
The Violence Project’s database: mass shooters are more likely to be unemployed, be unmarried, to have a history of mental health issues, to have lifetime thought disorders, and greater lifetime suicidal ideation, while in comparison to general homicide offenders, mass shooters four times more frequently premeditated their homicides, eight times more frequently killed strangers, were more likely to not be in an intimate relationship, and were more likely to experience suicidal ideation and commit suicide directly or by cop.
Many mass shootings are, in fact, angry suicides.
In a cross-sectional study examining 170 perpetrators of mass public shootings from 1996 to 2019, found that 44.3% of mass shooters had leaked their plans.
Leakage of such information is associated with receiving counseling and suicidality, suggesting the leakage may be a cry for help, and can be a time for mental health intervention to prevent tragedy.
Most mass shooters falling into a category of persistent emotional disturbance.
It is suggested that almost all mass shooting perpetrators have four qualities in common:
commonly experienced early childhood trauma and exposure to violence;
reached an identifiable crisis point in the weeks or months leading up to the shooting, often linked to a specific grievance
researched previous mass shootings, with many being radicalized through the internet;
obtained the firearms to carry out the plan, with perpetrators obtaining weapons from family members in 80% of school shootings.
Other research concluded a framework for mass shootings has four things in common: (1) early childhood trauma and exposure to violence at a young age; (2) an identifiable grievance or crisis point; (3) validation for their belief system, have studied past shootings to find inspiration; and (4) the means to carry out an attack.
It is thought that each one of the four themes represents an opportunity for intervention: reducing access to firearms, slowing contagion, training in crisis intervention de-escalation. and increasing access to affordable mental healthcare.
Mass shooters share a sense of entitlement and seek scapegoats when they fail to achieve goals in life, and that hate-motivated and fame-seeking mass shootings have been increasing.
A 2021 article in the journal Injury Epidemiology found that from 2014 to 2019, 59.1% of mass shootings in the United States were related to domestic violence, and the shooter either killed a family member or had such a history in 68.2% of mass shootings.
Other factors contributing to mass shootings is perpetrators’ desire to seek revenge for perceived school or workplace bullying, the gap between people’s expectations for themselves and their actual achievement,the perpetrators’ desire for fame and notoriety, toxic masculinity and a failure of government background checks due to incomplete databases and/or staff shortages.
Significant evidence exists that mass killings involving firearms are incentivized by similar events in the immediate past: this temporary increase in probability lasts 13 days, and each incident incites at least 0.30 new incidents.
There is significant evidence of contagion in school shootings, for which an incident is contagious for an average of 13 days and incites an average of at least 0.22 new incidents.
Mass shooters tend to be loners with not much social support who strike out at their communities, schools and families.
Several types of guns are used in mass shootings in the US, , including semi-automatic handguns, semi-automatic rifles, revolvers, and shotguns.
Rather than assault weapons, semiautomatic handguns are the weapons of choice for most mass shooters.
High-capacity magazines were used in more than half of mass shootings, and more than approximately 70% of mass shooters in the U.S. legally obtained the firearm used in the attacks.
Although semi-automatic rifles are used in only 1% of overall shootings in the U.S., they are used in 25% of mass shootings.
Mass shootings in the U.S. are associated with statistically significant increases in support for stricter gun control laws.
But such incidents have little to no effect on electoral outcomes in the United States, and have not led to meaningful policy reform efforts.
Mass shootings are associated with a variety of adverse psychological outcomes in survivors and members of affected communities, and that such events lead to at least short-term increases in fears and declines in perceived safety.
Risk factors for adverse psychological outcomes have include demographics, greater proximity to the attack, acquaintance with victims, and less access to psychosocial resources.
The United States has had the most mass shootings of any country, although the U.S. had less than 5% of the world’s population.
Mass shootings have also been observed to be followed by an increase in the purchase of weapons.
Survivors of mass shootings can suffer from Post-traumatic stress disorder.
The overwhelming majority of mass shooters in the U.S. are male, with some sources showing males account for 98% of mass shooters: compared to homicides in general in the United States, where 85.3% of homicides were committed by males.
The race of the mass shooters is approximately proportionate to the overall U.S. population, although Asians are overrepresented and Latinos underrepresented.
Research finings that 87.5% of mass shooter perpetrators had misdiagnosed and incorrectly treated or undiagnosed and untreated psychiatric illness.
The vast majority of people with mental illness are not violent, but almost all public mass shooters may have mental health problems.
Most mass murderers do not have a criminal record, or involuntary incarceration at a mental health center.
Mass shootings can be motivated by religious extremism, political ideologies, terrorism, White supremacism, racism, sexual orientation, misogyny, mental illness, and extensive bullying, among other reasons.
Some suggest extreme anger and the notion of working for a cause, rather than mental illness, as primary explanations.
Some contend that mass murderers are enabled by social isolation and typically experience years of disappointment and failure that produce a mix of profound hopelessness and deep-seated resentment.
Statistics show mass shooters have hopelessness and a need for notoriety in life or in death.
Some suggest that the individualistic culture in the United States puts the country at greater risk for mass shootings than other countries: many other countries where gun ownership is high, such as Norway, Finland, Switzerland and Israel, have more tight-knit societies where a strong social bond supports people through crises, and mass killings are fewer.
Mass shootings may be more due to the individualistic culture in the U.S. than its firearm laws.
There is a connection has been reported in the U.S. between mass shootings and domestic or family violence.
Almost all school shooters come from families where the parents are either divorced or alienated.
News media and social media enthusiasts should withhold the name(s) and face(s) of the victimizer(s) when reporting a mass shooting to deny the fame the shooters want, to curb contagion.