The distressing footage obtained by The Post opens with a man dressed in all black pacing angrily outside his upstairs neighbors’ apartment on the fourth floor of 1418 Brooklyn Ave. in a well-known East Flatbush housing complex where stars Barbra Streisand and Michael K. Williams grew up.

A woman emerges from the apartment and exchanges words with the neighbor, who was identified by cops Tuesday as Jason Pass, 47.

A short time later, the woman is joined by her son, identified by cops as 27-year-old Chinwai Mode. The video has no audio, so it is unknown what was said during the exchange.

Moments later, Mode’s stepfather, 47-year-old school bus driver Bladimy Mathurin, marches out of the apartment brandishing a pair of scissors and angrily confronts the neighbor, the video shows.

His wife tries to drag him away, but the bodybuilder dad of four pushes her back.

At that moment, the verbal dispute takes a harrowing turn when the neighbor in black pulls out a handgun and aims it at Mathurin.

Mathurin spots the gun but waves it off. He turns around and begins walking toward his apartment, at which point the neighbor opens fire and strikes Mathurin, who falls to the floor.

Mode, who was also in the hallway, tries to get away from the gunman, but the neighbor fires multiple shots at him, including at least twice after he had collapsed in a pool of his own blood next to a staircase.