Whatever pleasant reveries we were enjoying last Wednesday went up in smoke with the horrifying news of yet another school shooting, this one in Uvalde, Texas.

This one was particularly horrifying: 19 students and two teachers killed senselessly but methodically by an 18-year-old assailant; during his deadly 80-minute siege, children inside the school begged for help on 9-1-1 calls, parents waited helplessly outside, and dozens of police stood by impotently, waiting for reinforcements.

Public reaction was instantaneous: (1) Utter revulsion at the massacre of innocents, and (2) intense frustration that despite years of hand wringing, promises, and rationalizations, it keeps happening. Like a recurring nightmare, as fast as we push it away it comes right back, worse than ever.

There’s an understandable clamor for our leaders to “DO SOMETHING!” But all too often the “somethings” conjured up by politicians don’t do anything and at times make things worse. We need to take actions that can actually work — and fast.

To find them, let’s start by asking a simple question: What went wrong?

The killer was a very disturbed and angry young man (how do we detect such simmering, dangerous anger before it erupts?); he chose to act out his anger by murdering school children (was that seed planted by media coverage of other shootings?); he was able to acquire two AR-15s legally (why was he able to acquire a gun at all?); he shot his grandmother, stole her truck, crashed it and began firing wildly, all without being apprehended (why?); he was able to enter a school full of children, carrying long guns and a backpack full of ammunition (why so easy?); he then spent more than an hour in a room savaging defenseless victims before being stopped (why so long?)

In short, everything went wrong. Our systems — familial, societal, legal, protective — failed at every step. All need attention. Success at any point could have prevented the catastrophe; but we also can’t attribute those deaths to any single failure.

So, how do we dig out of this deep hole? There are some tough choices ahead, but this much I know:

• Protecting our children from senseless slaughter is an American issue, not a Republican or Democrat one. It is a quest that cries out for unified action. There is ample common ground, but no room for partisanship.

The last thing we need is bickering political opportunists trashing one another. But from the first report of an active shooter in Uvalde, that’s exactly what we got.

High-profile Democrats place the blame directly on Republican resistance to gun control legislation, despite any evidence or logic to suggest that any such legislation would have made a difference. Barack Obama referred to Republicans as “a political party that has shown no willingness to act in any way that might help prevent these tragedies.”

Rhetoric like that racks up a few political points, but it blocks all potential for collaboration.

• Job #1 must be single-minded commitment to prevent school shootings, now. We do that by making American K-12 schools ruggedly secure and safe, with controlled access, metal detectors, locked doors and windows, on-site protection service.

Some American schools are already down that track, but others — Uvalde’s Robb Elementary as a tragic example — are juicy, vulnerable targets. School protection is by far the most effective action we can take to prevent school shootings. It’s 100% doable. We can budget this work immediately, starting with unused COVID money, and use summer vacation to put in place the required physical modifications. Our kids will come back to safe schools in September.

• Obviously, there is much more to be done to address the broader issue of cultural violence. But those actions will take longer to implement, and longer still before having any significant beneficial effect.

Take gun control. Many sincerely believe that America has too many guns, and that they are too easy to acquire. Others note that America’s historically high gun ownership long predates the era of mass shootings. But in any case, the proposed measures to effect more rigorous background checks, raise age limits, prohibit manufacture and sale of certain gun types, once implemented, would leave untouched all those weapons already in circulation. However attractive, they would not prevent a school shooting next week, or even next year.

The myriad of other actions needed to address root causes of violence — mental illness, gang and other criminal activity, decline of effective parenting — are mountains to be climbed. Our challenge will be to keep them from falling into the never-neverland of “someday.”

But for now, first things first. No more school shootings.