NEW YORK (CBSNewYork) — The NYPD said its Internal Affairs Bureau is reviewing an incident after video of a violent confrontation between a teenager and police was posted online.

The incident happened Monday on Madison Street on the Lower East Side.

The video, which was posted Wednesday, shows three uniformed officers holding the teen while an officer in street clothing runs up and punches him twice.

In the video, one witness can be heard saying, “Hey, hey, hey! Stop it! Get off him.”

“There doesn’t seem to be any legitimate reason for it  The arrestee was pinned up against the hood of a car, he wasn’t moving at the time the blows were delivered and he was in no position to escape,” police procedure expert Robert McRie said, a professor at John Jay College.

Those witnessing the incident believed the boy to be 12 years old, but police said he’s 16.

The NYPD said the teen was arrested with two others for allegedly assaulting another person with a cane.

Sources told CBS2 the teen is Denzel Funderburk. He and the two other teens, ages 16 and 17, were screaming “murder gang” as they allegedly beat the victim, according to sources.

The 20-year-old victim suffered a broken jaw, sources said.

“An individual that we have identified as a plainclothes anti-crime officer runs up and appears to strike the individual with a closed fist twice on the side of the body,” Police Commissioner Bill Bratton said. “That officer has been suspended pending the investigation going forward.”

All three were charged with gang assault, sources said. Funderburk is also charged with assault, obstruction, criminal possession of a weapon and other charges, sources said.

“A police officer who does something like that to someone who’s already subdued is due for disciplinary action,” McRie said.

The case is now with internal affairs, CBS2’s Tony Aiello reported.

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