Why are U.S. mass killings in 2025 the lowest since 2006?

A shooting last weekend at a children’s birthday party in California that left four dead was the 17th mass killing this year—the lowest number recorded since 2006, according to a database maintained by the Associated Press and USA Today in partnership with Northeastern University.

Experts warn that the drop doesn’t necessarily mean safer days are here to stay and that it could simply represent a return to average levels.

“Sir Isaac Newton never studied crime, but he says ‘What goes up must come down,'” said James Alan Fox, a criminologist at Northeastern University. The current drop in numbers is more likely what statisticians call a “regression to the mean,” he said, representing a return to more average crime levels after an unusual spike in mass killings in 2018 and 2019.

“Will 2026 see a decline?” Fox asked. “I wouldn’t bet on it. What goes down must also go back up.”

The mass killings—defined as incidents in which four or more people are killed in a 24-hour period, not including the killer—are tracked in the database maintained by the Associated Press and USA Today in partnership with Northeastern University. Fox, who manages the database, says mass killings were down about 24% this year compared to 2024, which was also about a 20% drop compared to 2023.

Mass killings are rare, and that means the numbers are volatile, said James Densley, a professor of at Metropolitan State University in Minnesota.

“Because there’s only a few dozen mass killings in a year, a small change could look like a wave or a collapse,” when really it’s just a return to more typical levels, Densley said. “2025 looks really good in historical context, but we can’t pretend like that means the problem is gone for good.”

Decline in rates of homicide and violent crime might be a factor

But there are some things that might be contributing to the drop, Densley said, including an overall decline in homicide and violent crime rates, which peaked during the COVID-19 pandemic. Improvements in the immediate response to mass shootings and other mass casualty incidents could also be playing a part, he said.

“We had the horrible Annunciation School shooting here in Minnesota back in August, and that case wouldn’t even fit the mass killing definition because there were only two people killed but over 20 injured,” Densley said. “But I happen to know from the response on the ground here, that the reason only two people were killed is because of the bleeding control and trauma response by the first responders. And it happened on the doorsteps of some of the best children’s hospitals in the country.”

Crime is complex, and academics are not great at assessing the reasons behind crime rate changes, said Eric Madfis, a professor of criminal justice at University of Washington-Tacoma.

“It’s multicausal. It’s never going to be just one thing. People are still debating why homicide rates went down in the 1990s,” Madfis said. “It is true that gun violence and gun violence deaths are down, but we still have exceedingly high rates and numbers of mass shootings compared to anywhere else in the world.”

More states are dedicating funding to school threat assessments, with 22 states mandating the practice in recent years, Madfis said, and that could be preventing some school shootings, though it wouldn’t have an impact on mass killings elsewhere. None of the mass killings recorded in the database so far in 2025 took place in schools, and only one mass killing at a school was recorded in 2024.

Most of those who die in mass killings are shot

About 82% of this year’s mass killings involved a firearm. Since 2006, 3,234 people have died in mass killings—and 81% of them were shooting victims.

Christopher Carita, a former detective with the Fort Lauderdale Police Department and a senior training specialist with gun safety organization 97Percent, said the Safer Communities Act passed in 2022 included millions of dollars of funding for gun violence protection programs. Some states used the money to create social supports for people at risk of committing violence, and others used it for things like law enforcement and threat assessment programs. That flexibility has been key to reducing gun violence rates, he said.

“It’s always been framed as either a ‘gun problem’ or a ‘people problem’ and that’s been very contentious,” Carita said. “I feel like for the first time, we’re looking at gun violence as a ‘both, and’ problem nationally.”

Focusing on extreme events like mass killings runs the risk of “missing the forest for the trees,” said Emma Fridel, an assistant professor of criminology at Florida State University. “If you look at the deaths from firearms, both in homicides and suicides, the numbers are staggering. We lose the same number of people every year to gun violence as the number of casualties we experienced in the Korean War. The No. 1 cause of death for children is guns.

“Mass killings should be viewed as one part of the issue, rather than the outcome of interest,” she said.

—Rebecca Boone, Associated Press

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