Investigators in New Jersey are reviewing shocking video that shows an officer punching a woman during a melee outside a club in Elizabeth.

The 20-second clip, which was posted on YouTube on March 3, shows a group of people fighting outside Envy Night Club on North Broad Street.

The woman appears to tap the officer on the shoulder after he knocks another man on the ground. Without hesitation, the officer turns to the woman and pops her square in the face.

The sucker punch draws screams from witnesses including the camera operator. The video then abruptly ends.

Elizabeth police have not commented on the incident.