In the cellphone recording, a fight outside Envy Night Club escalates from yelling and cursing to a physical scuffle. The video ends after an officer emerges from the crowd and appears to hit one woman directly in the head.
Few details have surfaced, but Elizabeth police are looking into the incident, NBC New York reported.
At one point, a bystander chants"WORLD STAR," referring to a website that compiles videos of fights caught on tape. The 20-second clip is already up on the site.
An employee at Envy told The Huffington Post that the night club is aware of the situation, but could not offer any further comment.
A public information officer with the Elizabeth Police internal affairs department could not be reached.