Disturbing new video shows a straphanger knocked onto the train tracks and slashed by a knife-wielding man at one of Brooklyn’s busiest subway stations.

The frantic caught-on-camera attack unfolded on the southbound A and C tracks at Broadway Junction in East New York around 9:45 p.m. Wednesday, according to police and security footage.

A 52-year-old man walks past a suspect standing by a shopping cart who began to argue with him for an unknown reason, according to the video, released Saturday by the NYPD.

The suspect — brandishing a knife and wearing a black Nike sweatshirt — continues to exchange words with the other man, who eventually turns to confront him, the video shows.

The knife-wielding man then jabs at his adversary, who deflects the weapon and swings at him with what appears to be a jacket, the footage shows.

The men chase each other around the train platform, knocking over the contents of the suspect’s shopping cart as other straphangers are seen trying to get out of the way.

After a few seconds, the man in the black sweatshirt tackles the victim, causing them both to fall onto the subway tracks — where the slashing happens off camera, police said.

The victim was slashed in the chest, ear, finger and head before both men managed to get off of the tracks to avoid being hit by a train, police said.

The victim sought private medical treatment and the slasher was still at large, according to detectives.