A Florida officer’s life was spared in the largest mass shooting in US history this weekend and it was all because he was wearing a helmet.

The Orlando police department tweeted a chilling photo of a Kevlar helmet on Sunday with a dent where a bullet from an assault rifle might have otherwise penetrated the man’s skull. The officer’s identity was not immediately released.

The shooter, who killed at least 50 people and injured at least 53 at the gay Pulse Orlando nightclub early on Sunday morning, was identified as U.S. citizen Omar Mateen, law enforcement sources told The Post.

Mateen died after being shot by police.

The gunman, who was born to Afghan parents in 1986 and was living in Port St. Lucie, Fla., did not have a criminal history, according to multiple media reports.

“At this point, this is an incident, as I can see it, we can certainly classify as a domestic terror incident,” Jerry Demings of the Orange County Sheriff’s Office said.

Mir Seddique, shooter Omar Seddique Mateen’s father, told NBC News that the slaughter at Pulse in Orlando “has nothing to do with religion,” and that he recently became angered after seeing two men kissing.