Graphic video shows gang of Arizona cops punching out man on cellphone

Disturbing surveillance video has been released showing multiple police officers punching a man in the face in Mesa, Arizona.

Mesa Police Chief Ramon Batista has vowed an investigation and placed four officers on paid leave, 12 News reported Tuesday.

"The man is shown looking at his phone near an elevator, then officers walk up and hit him several times in the face and body," 12 News explained. "The elevator opens and more officers come out to join in."

After being repeatedly struck in his head, the man appears to lose consciousness before sliding down a wall and hitting the ground with a noticeable bounce.

The man was not a suspect, but was a friend of a suspect.

One of the four officers placed on paid leave was a sergeant, KVOA reports.