It could have been worse, but it wasn’t — thanks to “a good guy with a gun.” That’s what several conservative media outlets, from Breitbart to Fox News to the Blaze, are suggesting following the mass shooting at a Sutherland Springs, Texas, church on Sunday.

According to this narrative, an unnamed armed neighbor saved “countless lives” with his bravery after he intervened with his own weapon at the church shooting, pursuing the gunman who killed at least 26 people in Texas. The gunman was reportedly shot before he shot himself, Wilson County Sheriff Joe Tackitt told CNN.

The reports go back to an idea perpetuated by the National Rifle Association (NRA) for years: As the NRA’s Wayne LaPierre put it following the mass shooting at Sandy Hook Elementary School in Newtown, Connecticut, in 2012, “The only way to stop a bad guy with a gun is with a good guy with a gun.” Basically, if more people are armed, they can stop violence before it gets bad or prevent it altogether.

If Texas is an example of this concept in action, though, it sure doesn’t seem to work. Before another armed person intervened against the Sutherland Springs gunman, he had already killed at least 26 people and injured approximately 20 others. He managed to shoot more than 40 people before “a good guy with a gun” reportedly helped stop him.

Not to mention that if the gunman didn’t have access to firearms, “a good guy with a gun” wouldn’t have been needed in the first place.

But the theory has remained prominent in conservative circles — as the NRA has argued that the right to bear arms and lax gun laws are necessary not just to stand against government tyranny but also for self-defense and protection.

The Texas shooting exposes what this narrative gets wrong — more than 40 people were shot before another armed person intervened. But this was tragically predictable, because the reality is that there is a lot of evidence that “a good guy with a gun” can’t stop mass shootings and other gun violence in the US. Here are three key reasons why.

1) The research is clear: more guns, more gun deaths

Here is a simple fact that should underpin most conversations about guns: Where there are more guns, there are more gun deaths. This has been found repeatedly in empirical research on the matter.

We see this in cross-national data. Consider that America has nearly six times the gun homicide rate of Canada, more than seven times that of Sweden, and nearly 16 times that of Germany, according to United Nations data compiled by the Guardian. (These gun deaths are a big reason America has a much higher overall homicide rate, which includes non-gun deaths, than other developed nations.)

At the same time, the US has by far the highest number of guns in the world. According to a 2007 estimate, the number of civilian-owned firearms in the US was 88.8 guns per 100 people, meaning there was almost one privately owned gun per American and more than one per American adult. The world's second-ranked country was Yemen, a quasi-failed state torn by civil war, where there were 54.8 guns per 100 people.

The research shows these two statistics are connected. Regularly updated reviews of the evidence compiled by the Harvard School of Public Health’s Injury Control Research Center have consistently found that when controlling for variables such as socioeconomic factors and other crime, places with more guns have more gun deaths.

“Within the United States, a wide array of empirical evidence indicates that more guns in a community leads to more homicide,” David Hemenway, the Injury Control Research Center’s director, wrote in Private Guns, Public Health.

For example, this chart, from a 2007 study by Harvard researchers, shows a correlation between statewide firearm homicide victimization rates and household gun ownership after controlling for robbery rates:

A more recent study from 2013, led by a Boston University School of Public Health researcher, reached similar conclusions: After controlling for multiple variables, the study found that a 1 percent increase in gun ownership correlated with a roughly 0.9 percent rise in the firearm homicide rate at the state level.

This holds up around the world. As Zack Beauchamp explained for Vox, a breakthrough analysis in the 1990s by UC Berkeley’s Franklin Zimring and Gordon Hawkins found that the US does not, contrary to the old conventional wisdom, have more crime in general than other Western industrial nations. Instead, the US appears to have more lethal violence — and that’s driven in large part by the prevalence of guns.

“A series of specific comparisons of the death rates from property crime and assault in New York City and London show how enormous differences in death risk can be explained even while general patterns are similar,” Zimring and Hawkins wrote. “A preference for crimes of personal force and the willingness and ability to use guns in robbery make similar levels of property crime 54 times as deadly in New York City as in London.”

This is in many ways intuitive: People of every country get into arguments and fights with friends, family, and peers. But in the US, it’s much more likely that someone will get angry at an argument, pull out a gun, and kill someone.

Stricter gun laws can help prevent such deaths. Last year, researchers from around the country reviewed more than 130 studies from 10 countries on gun control for Epidemiologic Reviews. This is, for now, the most current, extensive review of the research on the effects of gun control. The findings were clear: “The simultaneous implementation of laws targeting multiple firearms restrictions is associated with reductions in firearm deaths.”

The study did not look at one specific intervention, but rather a variety of kinds of gun control, from licensing measures to buyback programs. Time and time again, they found the same line of evidence: Reducing access to guns was followed by a drop in deaths related to guns. And while non-gun homicides also decreased, the drop wasn’t as quick as the one seen in gun-related homicides — indicating that access to guns was a potential causal factor.

This all goes against the narrative put forward by the “good guy with a gun” theory. If it were true, then the spread of guns would lead to fewer gun homicides. But in reality, the opposite is true. So reducing the number of firearms in the US and preventing more people, like the Texas shooter, from obtaining them — through stricter gun laws — would save lives.

2) For every criminal killed in self-defense, there are dozens more murders

There’s another set of statistics that throws cold water on the “good guy with a gun” theory: It’s way more likely in America that someone will shoot and kill another person in the course of committing a crime than will do so in self-defense.

Christopher Ingraham at the Washington Post ran through the statistics. He looked at how many gun homicides, suicides, and accidental shootings there were in comparison to “justifiable” homicides (“the killing of a felon, during the commission of a felony, by a private citizen”), based on the FBI’s 2012 data.

His findings: For every justifiable gun homicide, there were 34 criminal gun homicides, 78 gun suicides, and two accidental gun deaths.

Other data suggests this applies to mass shootings as well. According to the FBI’s report on active shooter events between 2000 and 2013, only about 3 percent were stopped by a civilian with a gun. Unarmed civilians actually stopped more incidents — about 13 percent. Most of the incidents — more than 56 percent — ended on the shooter’s initiative, when the shooter either killed himself or herself, simply stopped shooting, or fled the scene.

This isn’t to downplay the heroism of people like the private citizen who intervened in the Texas shooting or others like him. But if you look at the statistics, it looks like guns are enabling much more death of the innocent than they are protecting people from a similar fate.

3) Even armed civilians typically can’t respond to a shooting in time

One reason the “good guy with a gun” theory by and large doesn’t work out in reality: Even when people are armed, that doesn’t mean they can properly respond to a mass shooting.

The Texas shooting demonstrates this. The armed neighbor only managed to respond after dozens of people were shot and killed.

Multiple simulations have also demonstrated that most people, if placed in an active shooter situation while armed, will not be able to stop the situation, and may in fact do little more than get themselves killed in the process.

This video, from ABC News, shows one such simulation, in which people repeatedly fail to shoot an active shooter before they’re shot:

As Chris Benton, a police investigator in Pennsylvania, told ABC News, “Video games and movies, they glorify gunfights. [People] get that warped sense that this is true — this video game is exactly what I can do in real life. That’s not reality.”

The Daily Show also put this theory to the test in another, more comedic, simulation segment. Jordan Klepper, who was a correspondent with the show at the time, trained on the basics of using a firearm and got a concealed carry permit that was valid in 30 states. Then he participated in mass shooting simulations to see how he would hold up in such a scenario.

He failed — miserably. In his final test, which simulated a school shooting, he shot an unarmed civilian, and he was shot multiple times by the active shooters and even law enforcement, who mistook him for the bad guy. He never took down the active shooters.

The fundamental problem is that mass shootings are traumatizing, terrifying events. Without potentially dozens or even hundreds of hours in training, most people are not going to be able to control their emotions and survey the scene in time to quickly and properly respond.

“There’s never enough training,” Coby Briehn, a senior instructor at Advanced Law Enforcement Rapid Response Training, told Klepper. “You can never get enough.”

So there’s almost never going to be “a good guy with a gun” at the scene of mass shootings. But even if there is, chances are he simply won’t be able to do much good.

If America wants to confront its gun violence problem, then, the research suggests it should look to stricter laws on firearms — not armed civilians.

Watch: America’s gun problem, explained in 18 charts