MONDAY, March 10, 2025 (HealthDay News) — A startling number of Americans have witnessed a mass shooting in their lifetime, a new study suggests.
About 1 in 15 adults have been present at the scene of a mass shooting, and more than 2% have been injured in one, researchers say in JAMA Network Open.
“This study confirms that mass shootings are not isolated tragedies, but rather a reality that reaches a substantial portion of the population, with profound physical and psychological consequences,” senior researcher David Pyrooz, a professor of sociology and criminology at the University of Colorado-Boulder’s Institute for Behavioral Science, said in a news release.
Younger generations are significantly more likely to have been in the middle of a mass shooting than their parents or grandparents, researchers found.
Generation Z – adults born after 1996 – are at greatest risk.
“Our findings lend credence to the idea of a ‘mass shooting generation,’ ” Pyrooz said. “People who grew up in the aftermath of Columbine have these unique experiences that are really distinguishable from the older population.”
He was referring to what remains as one of the most infamous school massacres in U.S. history. On April 20, 1999, two 12th-graders murdered 12 students and a teacher at Columbine High School in Colorado.
For the study, researchers surveyed 10,000 U.S. adults in January 2024. Participants were asked a series of questions, including “Have you personally ever been physically present on the scene of a mass shooting in your lifetime?”
Mass shootings were defined as a gun-related crime where four or more people were shot in a public space, and “physically present” as being in the immediate vicinity of the shooting, including being able to see the shooter or hear the gunfire, researchers explained.
Just under 7% of participants answered yes, researchers found.
“We are talking about one out of every 15 people in the United States,” Pyrooz added. “These are really high numbers for this seemingly unique and small subset of gun violence.”
In an accompanying editorial, Dr. Megan Ranney, dean of the Yale School of Public Health, agreed with Pyrooz’s assessment.
“Personal exposure of US residents to these events is outrageously high, given that mass shootings make up only 1% to 2% of annual gun deaths,” Ranney wrote.
The public nature of mass shootings means that these events create a ripple effect that impact far more people than many realize, Pyrooz said.
For example, 60 people were killed and 413 were wounded during the 2017 shooting at the Route 91 Harvest Music festival in Las Vegas, Pyrooz said.
But another 454 people were injured in the ensuing panic, trampled and knocked around as 22,000 concertgoers fled to safety, Pyrooz added.
In addition, onlookers from surrounding hotels on the Las Vegas strip witnessed the shooting.
“That translates to about one out of every 11,000 Americans who were on the scene of that shooting alone,” Pyrooz said. “Continue that to other events that have occurred around the country and the numbers, unfortunately, add up.”
More than half of those present at a mass shooting said in happened during the last decade, results show. Younger generations are experiencing a cultural phenomenon their parents never faced.
The study also found that men were 55% more likely to be present at a mass shooting, and Black people were 87% more likely.
In an upcoming paper, Pyrooz and colleagues will delve into how mass shootings affect mental health.
They expect to report that about 75% of people present at a mass shooting but uninjured still experience fear, anxiety, depression and other symptoms of psychological distress, Pyrooz said.
By comparison, only about 20% of average folks report these symptoms.
The picture in America is even more grim than portrayed in this study, Ranney noted.
By focusing on mass shootings, this tally dramatically underestimates the true impact of gun violence in the U.S.
“Despite the outsized attention of the media to mass shootings, exposure to firearm suicide (nearly two-thirds of firearm deaths) and firearm homicide (nearly two-thirds of firearm injuries, according to our best estimates) are much more likely than exposure to mass shootings,” Ranney wrote.
Pyrooz himself can still remember the sound of sirens from a 2021 mass shooting at a King Soopers grocery store just miles from his office in Boulder.
He wasn’t personally exposed, but he felt the toll the shooting took on his community.
“It’s not a question of if one will occur in your community anymore, but when,” Pyrooz concluded. “We need to have stronger systems in place to care for people in the aftermath of this tragic violence.”
More information
Johns Hopkins Bloomberg School of Public Health has more on firearm violence in the United States.
SOURCES: University of Colorado-Boulder, news release, March 7, 2025; JAMA Network Open, March 7, 2025
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