Police in Idaho just released body cam video of a fatal interaction with an autistic teen … and everything happens super fast.

Cops released footage Thursday and it shows officers from the Pocatello Police Department opening fire on 17-year-old Victor Perez just seconds after arriving at the scene and getting out of their squad cars.

The teen was on the ground in a fenced-in yard fumbling with a knife during a confrontation with family members when cops arrived … officers showed up, drew their guns and yelled at Victor to “Drop the knife!!!”

Perez stands up with a knife in his hand and takes a step toward officers, who are standing on the opposite side of a chain-link fence … and cops open fire. Officials say 3 officers fired handguns and another officer used a bean-bag shotgun. Two of Victor’s family members were standing behind him just off to the side.

Victor’s family says he was autistic, nonverbal and suffered from cerebral palsy … conditions police say they knew nothing about when they showed up at his house after getting a call about an allegedly intoxicated man armed with a knife.

Perez did have a blade, but his family says he wasn’t drunk, and they say he was stumbling around because of his disabilities.

The teen was reportedly shot 9 times and hospitalized in critical condition, where he had his leg amputated. He was removed from life support after being pronounced clinically brain dead a week after the April 5 shooting, and later died.

In the video, cops don’t appear to try and de-escalate the situation or figure out what’s going on with the teen … and the shooting has sparked outrage, protests and vigils in Pocatello.