President Donald Trump has responded to school shootings by proposing to arm teachers. He claimed during his most recent speech to the National Rifle Association that “the only way to stop a bad guy with a gun is a good guy with a gun.”

But the mass shooting that unfolded Sunday at a garlic festival in Gilroy, California, serves as a powerful refutation of the “good guy with a gun” myth — especially when the guns in question are high-powered weapons of war.

Consider this: After the 19-year-old Gilroy shooter opened fire with a WASR 10, a derivative of an AK-47, officers engaged him in less than a minute. That’s a very small window. Yet in that time, he was able to injure 15 people, including three who died from their wounds, before he was killed by officers. Videos from the chaotic scene indicate the gunman was able to fire off many more shots than just the ones that hit people.

It wasn’t as though officers were lucky to be in the area of the gunman when he started shooting. According to CNN, security at the festival was “present and conspicuous.” It included a police compound on site, officers on horses and motorcycles, bag searches, and metal detector wands. But none of that was enough to stop the gunman, who gained entry to the festival by cutting through a back fence before opening fire at random.

Trump has not yet publicly commented on the Gilroy shooting beyond offering condolences for the victims. But if past is precedent, his policy response won’t amount to more than some combination of increasing armed security at festivals and making it more difficult for people with mental illnesses to obtain firearms.

But none of those proposals would’ve helped in this case. A San Francisco Chronicle report finds the shooter had no criminal record, and he circumvented California’s strict gun laws by obtaining his WASR 10 legally in neighboring Nevada.

What would’ve prevented the shooting — or at the least made its outcome less devastating — would have been keeping a military-style weapon out of the shooter’s hands to begin with. But as my colleague German Lopez explained, the episode illustrates the limit of what states can do on their own in the realm of gun control laws:

The problem ... lies in federal and other states’ laws. As long as those are weaker, there’s going to be a limit to how well any stricter gun laws can work at the state level — for the simple reason that someone can always freely travel across the border to obtain a gun, whether for personal use or to sell to others. (This is illegal trafficking under federal law, but because other states’ laws are so weak, to the point they might not even require any sort of paper trail to complete a gun purchase, it’s really difficult to enforce the federal law.) The real solution, then, lies in changes to federal law. Only Congress and the president can set a baseline, such as universal background checks, an assault weapons ban, and requiring a license to buy and own a firearm, that all states will have to follow.

The Democratic-controlled House has passed a number of gun control bills this year, only to see them wither in the Republican-controlled Senate. So unless some Republican senators change their minds, it’s unlikely the loophole exploited by the Gilroy shooter will be closed anytime soon.

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