In the wake of another mass shooting, this time at a church in Texas, which killed 26 and injured 20, a Texas official repeated a similar argument on how the violence can be curbed: Good guys with guns stop bad guys with guns.
"We've had shootings at churches, you know, forever. It's gonna to happen again. And so, we need people in churches — either professional security or at least arming some of the parishioners or the congregation — so that they can respond, if something, when something like this happens again," Texas Attorney General Ken Paxton told Fox News hours after authorities said 26-year-old Devin Patrick Kelley donned a ballistic vest and opened fire on the congregation with an assault-style rifle.
It's the same line the National Rifle Association has been pushing since the Newtown shooting in 2012, when the group's executive vice president, Wayne LaPierre, said, "The only way to stop a bad guy with a gun is with a good guy with a gun."
In Texas, an armed neighbor did indeed confront the Texas gunman and, along with another neighbor, chased him for 11 miles before the gunman's car crashed after he shot himself.
But there's no evidence that more guns can reduce gun violence broadly, said Daniel Webster, Director of the Johns Hopkins Center for Gun Policy and Research at the Bloomberg School of Public Health.
"As a researcher, that drives me nuts," he said, explaining that guns increase the number of everyday moments or interactions — like bar fights, road rage, suicidal thoughts — that turn lethal. "The more guns are readily available, the more shootings occur. That's what the latest research shows. When states make it more easy for people to carry guns, the number of incidents of aggravated assault grows."
According to the Brady Campaign to Prevent Gun Violence, 93 people die a day from gun violence, including 32 murders and 58 suicides. A study out of Stanford Law School analyzed crime data from 1977 to 2014 and found that areas with more relaxed "right-to-carry" gun laws saw higher rates of violent crime.
"If more guns made America safer, we'd be an awfully safe place," said University of California Los Angeles law professor Adam Winkler, author of "Gunfight: The Battle Over the Right to Bear Arms in America."
A 2013 Pew study estimated that there are 270 million to 310 million guns in America, while the Census Bureau estimates that there are 326 million Americans living in the U.S. today.
"How many more guns? We have one per person. What do we need? Two-per-person?" he said in an interview with NBC News. "Just last year [Texas] loosened the laws making it so you were allowed to carry a gun into a church unless the church put up a sign. My understanding is this particular church didn't have one."
Research that would afford a more nuanced understanding of mass shootings and everyday gun violence or offer ideas for how to prevent shooting deaths is extremely limited, experts told NBC News.
In the mid 1990s, the gun lobby accused the Centers for Disease Control and Prevention of being anti-gun after a 1993 study found that keeping firearms in the home increased the risk of homicide by a family member or intimate acquaintance — and the National Rifle Association encouraged its congressional allies to target CDC funding. Congress passed a 1996 spending bill with the Dickey Amendment, a rider that barred government funds going to the CDC from being used to "advocate or promote gun control." Congress stripped the CDC of the $2.6 million spent annually on gun violence research.
"We hadn't been advocating gun control," Mark Rosenberg, who oversaw the CDC's gun violence research efforts at the time, told NBC News. "It was kinda a shot across the bow. It said, 'Look, if you keep doing this, we can make your life miserable.'"
The chilling effect was profound: 21 years later, government funding shies from digging into gun violence and prevention, even though Rosenberg argues there's nothing stopping them from rigorous research. Gun violence is the least-researched cause of death, according to a study published this year.
"Science is really, really powerful. In this area, it's been stopped. And as a result, we can't even answer the most basic questions. For cars, we register cars and we license drivers. It works. For guns, we don't even know if something as basic as registration and licensing works," he told NBC News in a phone interview. "We don't know — we haven't been able to do the tests."
He pointed to efforts to make motor vehicles and highway travel safer.
"We invested $200 million [a year] in research on how we could save their lives. We developed safer cars, we developed seat belts," he said, pointing to safer roads, air bags, and more.
"As a result, we've probably saved half a million lives since," he said. "We did that through science and through research without having to ban cars. We know what to do — we know that science can get us out of this."