Mass shooting

A mass shooting is a violent crime involving one or more attackers using firearms. These attackers kill or injure multiple individuals in rapid succession. This type of crime is often described as mass murder when it results in many deaths. A key feature of these events is that they often target people indiscriminately. This means the victims are not chosen based on a specific conflict. These incidents are typically different from gang violence, shootouts, or domestic violence. When an attack is currently happening, the person responsible is often called an active shooter.

Defining a mass shooting is difficult because there is no single, widely accepted definition. Different organizations use different criteria to track these events. The Mass Shooting Tracker defines an incident as any event where four or more people are shot. The Gun Violence Archive uses a similar rule, counting incidents where at least four people are shot, whether they are injured or killed. However, other groups like Mother Jones focus on the number of deaths. They define it as an indiscriminate rampage in a public place resulting in three or more victims killed. Because these definitions vary, it is hard to determine the exact number of people killed globally.

There are also specific legal definitions used by governments. For example, the Investigative Assistance for Violent Crimes Act of 2012 defines a mass killing as an incident with at least three deaths, excluding the shooter. In the United States, the Attorney General may investigate "mass killings" upon a state's request. The term "mass killing" was previously defined as the murder of four or more people without a cooling-off period. In 2013, Congress redefined it to include the murder of three or more people. Sometimes, a mass shooting is also classified as terrorism. This happens if the act is intended to intimidate or coerce a population.

Motivations for these crimes vary widely among perpetrators. Some individuals act due to personal or psychological reasons. They may feel deeply disgruntled or intensely angry about a perceived grievance. Others may seek notoriety or fame through their actions. Some researchers believe that media coverage of previous shootings can motivate people who want to be famous. In other cases, mass shootings are used as a terrorist tactic. This occurs when attackers deliberately target specific ethnic or religious groups to cause fear.

The United States has the highest number of mass shootings in the world. In 2021, the statistics showed how much definitions matter. Using the FBI's definition of active shooter incidents, there were 103 deaths. However, using the Gun Violence Archive's definition, the number of deaths reached 706. A 2016 study by Adam Lankford estimated that 31 percent of all public mass shooters from 1966 to 2012 attacked in the U.S. This was significant because the U.S. holds less than five percent of the world's population. Later research suggested that while the U.S. has a high share of single perpetrators, the exact proportions are still debated by experts.

Mass shootings appear differently depending on the country and its laws. In China, private ownership of firearms has been prohibited since 1951. Japan has very low rates, with as few as two gun-related homicides per year. In contrast, mass shootings have become common in Mexico due to violence from drug cartels. Brazil also faces high rates of gun violence. In 2022, Brazil had at least 10 mass shootings that killed over 50 people. In 2017, the country saw over 45,000 gun-related homicides. In many parts of Africa, these incidents are considered relatively rare, though terrorism and ethnic conflict can cause mass violence.

These events have a profound impact on human mental health. Survivors often suffer from post-traumatic stress disorder and survivor's guilt. This guilt is a heavy emotional burden that can lead to tragic outcomes. For example, in 2019, two survivors of the Parkland high school shooting committed suicide due to survivor's guilt. The trauma also affects first responders and the loved ones of victims. Studies show that people with limited social support or high exposure to the event face higher risks of depression. These long-term psychological effects remain a central concern for communities after an attack.

Mass shootings often lead to significant societal changes and legal scrutiny. When firearms used in a crime were purchased legally, it often prompts discussions about gun laws. Significant shootings in the past have directly contributed to stricter firearm restrictions. For instance, shootings in Dunblane, Port Arthur, and Christchurch led to expanded laws in the United Kingdom, Australia, and New Zealand. These events show how communities respond to violence by attempting to change the systems that allow it to happen. Such changes reflect a global effort to manage the impact of firearm-related crime.