Rifle-toting NYC shooter critically injures 3, including cop, before turning gun on himself inside Blackstone, NFL HQ

A crazed gunman wearing a bulletproof vest opened fire inside a swanky Midtown skyscraper that houses Blackstone and NFL headquarters Monday, injuring three people, including a cop — before turning the gun on himself, sources said.

The man entered the building armed with a rifle, law enforcement sources told The Post.

At least one police officer was shot at the scene and is in critical condition. Two civilians were also struck by gunfire — one of which is also in critical condition, sources said.

The suspect barricaded himself inside and was found dead from a gun-inflicted gunshot wound on the 33rd floor, sources said.

A witness on the first floor said that “it sounded like a barrage of shots …Like an automatic weapon. Like a high-capacity weapon.”

The injured officer was working in the building on a paid detail, sources said.

This is a breaking story. Please check back for updates.