LEILA FADEL, HOST:
Each time there's a mass shooting, like those in Uvalde and Buffalo, the question is raised - how can attacks like these be prevented? Scientists who study gun violence say there is some evidence suggesting that certain kinds of gun laws might help. But as NPR's Nell Greenfieldboyce reports, definitive answers are hard to come by.
NELL GREENFIELDBOYCE, BYLINE: Of the 40 to 50,000 people who are killed by guns each year in this country, less than 1% die in mass shootings.
MIKE ANESTIS: They're horrific. They are all too common. And yet, it's just the very tip of the iceberg, right?
GREENFIELDBOYCE: Mike Anestis is executive director of the New Jersey Gun Violence Research Center at Rutgers University. He says research into all forms of gun violence has long been neglected. The federal government hardly funds it.
ANESTIS: There is money out there. But it is really far below where it should be, given the amount of injury and death and economic costs associated with gun violence. It's just disproportionately underfunded.
GREENFIELDBOYCE: And he says those researchers who do study gun violence tend to focus on what causes the most deaths, like suicide.
ANESTIS: Mass shooting research is a very small portion of gun violence research.
GREENFIELDBOYCE: Still, some studies have looked at mass shootings and what might prevent them. Daniel Webster is co-director of the Johns Hopkins Center for Gun Violence Solutions. He says in the U.S., laws related to guns vary from state to state.
DANIEL WEBSTER: That is, honestly, less than ideal from a public safety standpoint. But it does provide researchers with opportunities.
GREENFIELDBOYCE: Because they can compare states to try to tease out the effects of various laws.
WEBSTER: I have to sort of acknowledge that this is a really hard and, frankly, inexact science.
GREENFIELDBOYCE: He and some colleagues recently looked at over 30 years of data on shootings in the U.S. that involved four or more victims.
WEBSTER: We did find two policies that had significant protective effects in lowering rates of fatal mass shootings.
GREENFIELDBOYCE: One was a requirement that a gun purchaser go through a licensing process.
WEBSTER: A licensing process requires someone to, you know, directly apply and engage with law enforcement sometimes or safety training and other requirements.
GREENFIELDBOYCE: Webster says another approach that seemed to reduce deaths from mass shootings was state bans on buying large-capacity magazines or ammunition-feeding devices for semi-automatic weapons.
WEBSTER: The greater ammo capacity that you have in a semi-automatic firearm, the more bullets you can fire uninterrupted in a short amount of time.
GREENFIELDBOYCE: But if a shooter has to stop and reload, victims could escape or fight back. He says there's other policies that might help as well, like so-called red flag laws that allow police officers to temporarily take guns away from people who seem to pose an imminent danger. One study in California found 21 cases of this process being used over a two-year period because someone threatened to commit a mass shooting. Several of those threats involved schools. Webster says research also shows that...
WEBSTER: The peak ages for violent offending with firearms is roughly 18 to 21.
GREENFIELDBOYCE: People under 21 aren't allowed to drink beer. But the shooter in Uvalde was able to legally buy semi-automatic rifles just after his 18th birthday. So Mike Anestis says it's reasonable to ask, would age restrictions make it harder for young adults to access weapons capable of creating a mass shooting?
ANESTIS: Yeah, it might. Do we have large data-based resources to evaluate those policies? No, we don't.
GREENFIELDBOYCE: It's just one item on the long list of things gun violence researchers wish they understood.
Nell Greenfieldboyce, NPR News.
(SOUNDBITE OF JUAN RIOS' "I WISH (INSTRUMENTAL VERSION)")
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