Man Throws Woman Onto NYC Subway Tracks in 'Unprovoked Attack'

Cops in NYC are looking for a man after this horrifying video surfaced of the guy throwing a woman onto subway train tracks -- an act of violence authorities are calling totally unprovoked.

This attack went down Sunday in the Bronx -- the video shows a guy grab a lady by the shoulders and shove her down to the ground, off the subway platform and onto the tracks. Chillingly, he casually walks away from the scene.

Law enforcement sources tell us the shove seems to have come out of nowhere, for no apparent reason ... and the woman suffered a broken collar bone and lacerations to her head.

NYPD is asking for assistance in identifying the man, who's so far gone uncaptured.

After the attack, the man is said to have fled without further incident, and people standing nearby helped the woman off the tracks. She was taken to a hospital in stable condition.