A school resource officer who worked at Marjory Stoneman Douglas was on campus at the time of the mass shooting, but did not enter the building to engage the killer—even though the SRO was armed.

Broward County Sheriff Scott Israel suspended the SRO, 54-year-old Scot Peterson, after watching video footage of Peterson declining to enter the school during Nikolas Cruz's six-minute rampage; Peterson has now resigned, according to The Washington Post.

When asked what Peterson should have done, Israel told reporters in no uncertain terms that the officer had a responsibility to confront the killer and attempt to stop him.

"I think he took up a position where it looked like he could see the western-most entry into the building and stayed where he was," said Israel. "Never went in."

Peterson's failure to act made Israel "sick to my stomach," the sheriff said.

Two other officers have been placed on restricted assignment pending an investigation; we don't yet know whether these officers are guilty of similarly bad judgment.

Make no mistake—Peterson's failure to engage the shooter was a monumental error. We don't know whether the SRO would have been able to stop a psychopath armed with an AR-15, but it was his job to try; he might have at least slowed Cruz, thus saving lives. Why are we paying armed guards to keep schools safe if they flee the very danger they are supposed to prevent?

It's difficult to fathom the depths of law enforcement's collective failure—at every conceivable level—to take any action that might have averted the Parkland tragedy or mitigated the death toll. The FBI didn't follow-up on tips about Cruz's verified instability. Broward County didn't take preventative measures despite receiving more than 20 calls about Cruz over the years. And the officer whose job it was to keep kids safe stood idly by while they were murdered—even though one of the big lessons of Columbine was that lone officers should rush toward the sound of gunfire in school shooting scenarios.

At the very least, these revelations about the abysmal incompetence of law enforcement should shake our confidence that more cops, more security, and more surveillance are the solution to mass shootings—and that the corresponding civil liberties tradeoffs are remotely justified.