There's a lot of chatter right now about reports that police waited quite a long time before police entered in force the Texas elementary school where a shooter had murdered nearly two dozen people. Much of that chatter is of a very typical brand of Twitter discourse of the "what good are cops, what were they waiting for, they're cowards, even in a situation like this they won't risk they're lives" variety.
I think that at least some of this criticism, though not all of it, is probably unfair. But more to the point: it is because I think that some of this criticism is probably unfair that I am very confident police responses are not going to stop another Uvalde.
Here's the blunt truth: a school shooter, who does not care about his own life and hopes to kill as many other people as possible, has (to put it extremely bloodlessly) flexibility that those trying to stop him do not. To take one example: the gunman can, whenever he wants, enter any room he wants firing entirely indiscriminately. The police, by contrast, cannot simply enter any room they want firing indiscriminately; nor would we want them to. It's not a matter of courage, or numbers; it is a structural imbalance that favors the gunman over those trying to stop him.
But that's exactly why all this talk of "hardening the target" or bringing even more cops with more guns is so clearly not a viable response. Putting aside (though we shouldn't) the problem that this "solution" is basically to convert our schools into fire traps or prisons. Once a shooter is on site with a gun and a disregard for human life, they have a built-in advantage that no amount of police presence can fully reverse. Sometimes their rampage will be stopped earlier, other times later, but it's all mostly a matter of luck. Short of turning schools into bunkers, the idea that the "right" security measures can stop a man who doesn't care about his own life and can freely and easily access high-powered weaponry without breaking a sweat is nonsense.
I have no idea whether the Texas police who were on site during the Uvalde shooting responded with ideal tactics. And, as awful as it is to say, if a shooting is ongoing, there really isn't much replacement for bringing it to an end other than armed officers. But if a shooting is ongoing, we've already failed in the most relevant respects. If the goal is to prevent these shootings from occurring outright, not to shrug our shoulders and say "it could have been worse", armed police are not going to do much good -- and it has nothing to do with courage, or armament, or tactics, or temperament.