NYPD Plainclothes Cop Appears To Punch Restrained Teen (RAW VIDEO, UPDATED)

A plainclothes NYPD officer appears to punch one of two teenagers during an arrest captured on video.

The video, uploaded to YouTube last Monday, shows three officers restraining the teenager. Suddenly, a plainclothes officer hurls himself onto the suspect, punching him twice in the back.

UPDATE: Dec. 19 -- Later on Friday, the NYPD said that the officer had been suspended, WNBC reported.

The NYPD's Internal Affairs is now investigating the incident, the New York Daily News reported.

"Stop it, get off of him!" the person taking the video -- identified as Sarah Doneghy -- can be heard shouting.

"He's 12, he's 12!" another woman shouts. "I can't believe you just did that to him, after everything that's been happening."

More from Doneghy, via her YouTube upload:

Today, a little after 4 pm I was walking to the post office on the Lower East Side in Manhattan. I witnessed these kids being beaten and handcuffed. A woman was yelling that they were only 12. They had supposedly knocked down a schoolmate. When the victim was questioned he said that it wasn't them. The kids were still taken away. 12. Years. Old.

The NYPD told the Daily Mail that the suspect who was punched is actually 16 years old. The two teens denied any wrongdoing, but police said they were arrested for assaulting someone who was walking with a cane.

Doneghy could not be immediately reached for comment.