Within hours of the school shooting in Uvalde that left 19 students and two teachers dead, Texas Sen. Ted Cruz said armed police need to be stationed in elementary schools. Former President Donald Trump advocated for armed teachers and metal detectors days later in a speech at the National Rifle Association’s annual meeting. Texas Attorney General Ken Paxton dismissed the idea of stronger gun laws in lieu of arming and training citizens.
The political talking point of increasing the presence of police and armed teachers to deter mass shootings traces its origins to 2012—having been famously proposed by NRA head Wayne LaPierre following the shooting at Sandy Hook Elementary School, where 20 children and six staff members were killed. “The only way to stop a bad guy with a gun is a good guy with a gun,” he said, as the nation debated tougher gun control measures.
But in the 10 years since, “good guys with guns” have been present or quickly arrived at the scene of nearly every major mass shooting and failed to stop the gunman before he was able to take multiple lives. “Good guys with guns don’t always win gunfights,” says David Hemenway, director of the Harvard Injury Control Research Center and the Harvard Youth Violence Prevention Center.
In the May 14 mass shooting at a Buffalo, New York supermarket, Aaron Salter—an armed security guard and former police officer—was hailed for his efforts at trying to protect others. At least one of his bullets hit the shooter, but the gunman was protected by an armor-plated vest and he fatally shot Salter—one of 10 victims.
Armed individuals have also been present at the site of major several mass shootings since Sandy Hook. Police and security guards were present at the Route 91 Harvest Music Festival in 2017, and in the Mandalay Bay Hotel where the gunman was located. Sixty people were killed, and more than 400 wounded. At the Pulse nightclub shooting in June 2016, an armed security guard shot at the gunman, who killed 49 people. (Although initially lauded as a hero, some victims’ family members sued the off-duty officer, alleging he remained outside of the establishment to protect himself.)
Armed guards have also failed to stop shooters in schools. In 2018, a shooter killed 10 people at Santa Fe High School in Texas even though two officers were on site and one was wounded trying to stop the gunman. Earlier that year, a school resource officer was on campus at Marjory Stoneman Douglas High School in Parkland, Fla.—although he was accused of hiding during the mass shooting, rather than rushing in.
The situation is even more complicated in Uvalde, where conflicting accounts of events have emerged and the police response is being widely criticized. Local police waited for more than an hour before a U.S. Border Patrol tactical team arrived and stormed the classrooms where the gunman barricaded himself—killing him. Texas Department of Public Safety head Steven McCraw said waiting was “the wrong decision, period,” and police conduct is being investigated by the U.S. Justice Department.
However, the first police officer responded to Robb Elementary School within one minute of the initial reports of a gunman with an AR-15 semi-automatic rifle—before the shooter had even entered the school.
“Sometimes having a gun is useful but a lot of times it makes things worse, even when there’s a clear bad guy,” says Hemenway. Perpetrators of mass shootings are more likely to be armed with semi-automatic weapons and high-capacity magazines, which make them capable of firing dozens of rounds. Some—like the gunman in Buffalo—also wear body armor. “Bad guys get such military-style weapons, and now wear protection so that even if you shoot them, they may not get hurt,” Hemenway adds.
Research disputes recent assertions from Cruz and others that armed law enforcement on campus is “the most effective tool for keeping kids safe.” A 2021 JAMA Network Open study analyzed every documented incident from 1980-2019 in which “one or more people was intentionally shot in a school building during the school day, or where a perpetrator came to school heavily armed with the intent of firing indiscriminately.” It found “no association between having an armed officer and deterrence of violence.” “When there’s more guns, more people die,” says Jillian Peterson, one of the author’s of the JAMA study.
A 2015 Harvard University study Hemenway worked on that analyzed data from 2007 to 2011 found that of more than 14,000 crimes in which a victim was present, just under 1% involved a gun used in self defense. The Harvard Injury Control Research Center also found that self-defense gun use is “rare and not more effective at preventing injury than other protective actions.”
Moreover, perpetrators are often at a strong advantage in mass shootings; it’s extremely hard to intervene once a killer is on site. Experts say that’s partly because shooters can afford to be much more unpredictable, since they are expecting to either die or be caught. Victims of a shooting attack, meanwhile, often respond in understandably chaotic and panicked ways. “The shooter is not necessarily worried about getting out of the situation alive. The average person or responding officer is concerned about surviving. You have something to lose. So that’s a huge disadvantage,” says Emma Fridel, an assistant professor of criminology and criminal justice at Florida State University.
That has led many who have studied mass shootings to conclude that by the time someone with the intent to kill shows up at a school, or a supermarket, or a house or worship with a gun, it’s too late to stop bloodshed. “The best way to prevent problems is to go upstream and really try to prevent things rather than wait until they’re about to happen,” Hemenway says. “There’s no reason why we need to have AR-15s or AK-47s in civilian hands. That’s sort of crazy.”
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Write to Sanya Mansoor at sanya.mansoor@time.com