Since 2006, guns have been used in an average of 25 mass killings per year in the United States, killing 2,476 people in all. We use the term “mass killing” to describe events in which four or more people died, not including the perpetrators. These violent episodes have occurred 11 times since the beginning of 2024.

Some shooters target strangers in public, firing at children in schools, shoppers in stores, worshipers in sacred spaces. Many of these events are so familiar that the locations are now shorthand for the horrors that occurred there: Parkland, Virginia Tech, the El Paso Walmart, the Tree of Life synagogue.

However, many more mass shooters strike in homes, intentionally killing people they know, love or once loved, and few outside the immediate community may hear about it or remember it. Do you recall a Chicago man who fatally shot neighbors in his condominium building as they sat down to dinner in 2019? Or the father in Gustine, Calif., who killed his four children then himself in 2006?

There are also mass killings that happen during the commission of other crimes, such as drug deals or robberies. The Post is calling these events “mass killings with guns” because it is more specific than the term “mass shooting.” There is no standard definition of a mass shooting, and some news organizations and gun violence trackers include events in which multiple people are injured but no one dies.

This project explores the people lost, the shooters and the circumstances surrounding mass killings using data compiled by the Associated Press, USA Today and Northeastern University.

The numbers reveal most mass killings are not random bursts of public violence but private ones that are not random at all.

Tap and hold a person for more information

was one of 0 people killed on undefined NaN, NaN, in , .

A team of data scientists in 2015 found that mass shootings are temporarily contagious and sometimes occur in clusters, with two or more within a few days, then none for weeks.

There were 39 mass killings with guns in 2023, and nine occurred in January.

While gun violence overall tends to increase in the summer, mass killings with guns seem to have no pattern. Dozens have occurred in every month of the year.

Explore this series

Where do mass shootings happen?

What do we know about the shooters?

How common are other types of mass killings?

We hear most about the shootings in which many people are killed, but they represent a small slice of U.S. gun deaths and an even smaller part of everyday gun violence.

More than 48,000 people were killed by gunfire in 2022, according to the most recent provisional data from the Centers for Disease Control and Prevention, and about 56 percent of those were suicides. Anti-gun-violence organization Brady United calculated that more than 325 people are shot on an average day in the United States.