Image captured from YouTube.com
13WHAM Reports: An investigation is underway in a case of alleged police brutality in Buffalo.
A viral video, posted online Thursday, sparked the investigation.
In the video, a male suspect appears face down on the sidewalk, with as many as four police officers holding him down.
The suspect is repeatedly heard saying, "Officer, please stop" and "I'm sorry" and yelling in pain.
An officer is seen on the tape slapping and kicking the victim in the head as he lay on the ground handcuffed.
WARNING: THIS VIDEO CONTAINS VIOLENCE AND BAD LANGUAGE. VIEWER DISCRETION IS ADVISED.