BRIDGEPORT, Conn. (WHDH) -- A YouTube video showing questionable conduct by police in Bridgeport, Connecticut has led to an investigation.

The video shows officers kicking a man while he is on the ground.

The incident happened in May of 2011, after the officers had apparently used a stun gun to subdue the man.

The Bridgeport Police Department learned of the video earlier this month.

Officers say the man on the ground never filed an "excessive force complaint.”