THIS IS WHAT COPS DO ALL THE TIME! THEY BEAT A HANDCUFFED MAN ON THE GROUND!

A Bronx pit bull attack that prompted the friendly-fire shooting of two undercover cops took a tables-turning twist Thursday when a gotcha video surfaced showing blatant police brutality.

"We simply are never going to tolerate something like that," said Police Commissioner Raymond Kelly, who viewed the video shot Jan. 5 by a private citizen.

The video, turned over to the Bronx district attorney, shows Officer John Cicero, 28, repeatedly punching Jonathan Baez, 28, in the head as he lies splayed and handcuffed on the sidewalk.

Officer William Green, 26, also is seen allegedly punching and kicking the defenseless man. They have been suspended.

Two sergeants - Junior Carela and Phillip Connor - who witnessed the attack but did not intervene, were put on desk duty.

"I felt horrible," said Baez, whose lawyer, Jeffrey Emdin, announced a pending multimillion-dollar lawsuit against the NYPD.

"This is not an isolated incident," Emdin said. "What sets this apart is that it was caught on tape."

The alleged brutality occurred after two undercover cops were hit by bullet fragments fired by a colleague being attacked by a pit pull.