A Horror in The Bronx

Well, so much for Mayor de Blasio’s happy talk about rising school safety. One high-school student is dead, and another is clinging to life after Wednesday’s incident at the Urban Assembly School for Wildlife Conservation in The Bronx.

Police say Abel Cedeno, 18, plunged a switchblade into the chests of two other teenagers — apparently after years of bullying and harassment by other students.

The city responded with a massive tightening of security in the building Thursday, as well as a visit by de Blasio and Chancellor Carmen Fariña. We doubt his talk about his own worries as a parent was much comfort to the worried parents.

After all, his kids went to high-performing, low-crime schools. Urban Assembly, according to what teachers and students say in the city’s “school climate” surveys, hasn’t been safe for some time now.

Of course, horror can strike in even the best school. But we’ve warned that the mayor’s softening of school discipline is risky.

He has made it harder for school-safety agents to arrest students for offenses such as disorderly conduct, harassment or criminal mischief. And teachers are prohibited from calling for the assistance of safety agents over acts involving bullying, vandalism and so on.

Even United Federation of Teachers boss Mike Mulgrew, a strong de Blasio ally, has questioned some of the changes.

The Manhattan Institute’s Max Eden’s analysis of school-climate surveys was another warning sign. He found that the softer approach “intended to help minority students has hurt them the most.”

Fariña’s minions responded by making changes to the surveys, which conveniently makes it harder to measure whether things are getting better or worse.

Greg Floyd, president of the safety agents’ union, this year predicted that “the probability of serious incidents and injuries grows daily.”

Let us all pray that the mayor changes course before more children wind up dead.