A shooting horror was averted last Monday. Who knows? Maybe another massacre, given the volatile combination of a disturbed war veteran’s escalating mental crisis and the astounding firepower he had accumulated preparing for Armageddon.

He was an Iraq War veteran, 26, suffering from crippling effects of post-traumatic stress disorder. His relatives were convinced that with his ever-deepening delusions and with the frightful armory he kept in his West Miami-Dade home, the vet was on the verge of something terrible.

It was only luck, and a Google search, that led them to the right telephone number. They called the office of Judge Steve Leifman, architect of the county’s mental health intervention project. Leifman’s staffers, Cindy A. Schwartz and Habsi Kaba, took the information and dispatched a crisis intervention team to the house. Along with a SWAT team.

Miami-Dade police negotiator Victor Milian, a vet himself, spent more than five hours talking down someone beset by apocalyptic paranoia, obsessed by some notion that President Obama’s reelection was tied to that Mayan calendar end-of-the-world craziness. Milian — Leifman described his work that day in heroic terms — finally convinced the besieged man to surrender. He was taken to one of the county’s mental crisis stabilization units.

It was what police found inside the house that shook Leifman. The vet had covered his walls with strange paintings and apocalyptic slogans, “all must die,” and “the world is ending,” and numbers and dates, Leifman said, that “all run together.” The vet taped shooting range targets, black silhouettes with human shapes, on his walls. Leifman said it was clear, from the tight clusters of bullet holes, that the former soldier was a very good shot.

Leifman said the siege-obsessed man, wearing full-body armor, had arrayed 10 assault rifles through the house, as if he had intended to scurry from window to window, repelling invaders. Leifman said police found thousands, perhaps as many as 10,000 rounds of ammo. Relatives had also warned Leifman’s staffers that they had seen grenades, though police found none when they searched the house on Monday.

“It scared the hell out of me,” said Leifman, after examining police photos taken in the interior of the fortress house. “It was a perfect storm. A very frightening prospect. He was in decompensation, mentally, in a full tailspin. With all those weapons, we could have had something as horrible as Sandy Hook.”

On the Saturday before and again on that Sunday, Sweetwater police officers, with no idea what kind of firepower they were confronting, had knocked on his door, unwittingly attempting to execute an order to take the man to a crisis stabilization unit. He didn’t answer the door, else there might have been deadly confrontation.

But here’s the thing. All those assault rifles were legally purchased. The vet even had a state-issued permit to carry a concealed firearm.

Because he has never been charged with a crime and because he has never officially been pronounced mentally ill, he had a perfect right to turn his house into an armory. And unless he agrees to a hospital commitment, Leifman worried, the vet may walk out of the crisis stabilization unit after his mandatory seven days and demand that police return his weapons.