In the midst of a nationwide debate about school shootings, and only days before the “March for Our Lives” will take place in Washington, D.C., another school shooting happened this week at Great Mills High School in Maryland. This time, however, the script was a little different: the shooter was stopped by an armed School Resources Officer.

The shooter entered the school with a Glock semi-automatic pistol and was confronted by the SRO moments after he shot two students, a boy and a girl. According to reports, the girl and the shooter had a prior relationship, so it is possible that the intent was a targeted killing rather than massacre. Or, the shooter could have intended to keep going. The boy was shot in the thigh and recovered, but, unfortunately, the girl, Jaelynn Willey, was taken off life support on Thursday.

This event underscores and oft-repeated but still misconstrued truism: adding more armed protection to schools is a reasonable and proportionate response to school shootings. Such policies are likely to save more lives than any gun-control policy that has even a moderate chance of being passed—whether raising the age limit for purchasing rifles, banning “assault weapons,” banning “high-capacity” magazines, or something else. And while you’re free to complain about the members of Congress who block purportedly “common-sense” gun control, they’re there now and they’ve proven to be quite resilient. Protecting our schools is vitally important and something needs to be done now, not 20 years from now.

That could mean many things, from increased police presence at schools, to arming teachers, to keeping guns in locked boxes accessible to a few trained staff (as is happening in Ohio), to private security services. Each of these has benefits and drawbacks. Increased police in schools tends to lead to the “criminalization of typical teenage misbehavior.” Arming teachers can lead to accidents, as happened last week in California. Private security guards can harm the educational experience by making schools seem more like prisons. Choices and trade-offs will have to be made.

In other contexts, increasing security around potential targets would not be a controversial move. If a serial night burglar or rapist were stalking your neighborhood, the reasonable first response would be to secure your home, perhaps through extra locks, a security system, or, if you’re comfortable, a gun. Broader preventative measures would come next—such as changes to police policies, gun control, or trying to address the social roots of criminal activity—but those wouldn’t see results for months or years to come. The immediate problem is protection.

But, for supporters of more restrictive gun control, increasing armed protection at schools sounds like the ravings of someone who’d rather live in the Wild West than in a civilized society. It’s pouring gasoline on the fire.

I understand this sentiment. I don’t like guns very much. I don’t own guns. I understand those who would like to live in a gun-free world, but in America that’s a fantasy.

Let’s return to the real world, where kids are walking into schools with guns, and there are currently between 300–400 million out there for them to choose from.

Yes, it can be argued that gun-control laws in other countries helped stop mass shootings, and perhaps they did, but America is different. Even if we stopped all gun sales tomorrow and repealed the Second Amendment, school shooters are unlikely to be deterred. They are particularly determined killers, usually planning their crimes months in advance, which includes stockpiling weapons and magazines, building bombs, and other disturbing scheming. “Assault weapons” may seem ominous, but school shooters don’t commit their crimes because they have assault weapons, they seek out assault weapons once they decide to commit their crimes. And if there weren’t any “assault weapons,” there are more than enough other kinds of guns out there for them to commit their atrocities.

School shooters should be seen more like serial killers than normal criminals. Serial killers aren’t dissuaded by waiting periods, background checks, or other laws that could feasibly discourage less-motivated criminals. If a serial killer was terrorizing America with a specific brand of chef’s knife, it would be ludicrous to ban that brand of chef’s knife, especially if there were millions already in circulation.

Protection and better detection are the most realistic ways to prevent and catch serial killers and they’re also the most realistic ways to prevent mass shootings. Perhaps, through concerted political action and protests, Americans will slowly change their minds about guns and one day more stringent gun control will be possible. That day, however, is not today.

Today is the day to protect our schools.