'Boardwalk Empire' Star Michael Stuhlbarg Attacked By Homeless Man With Rock

"Boardwalk Empire" star Michael Stuhlbarg was attacked by a homeless man with a rock, TMZ has confirmed.

Law enforcement sources tell us the actor was out jogging in Manhattan on Sunday around 7:45 PM when he suddenly felt something strike the back of his head.

We're told when he looked down, he noticed a rock lying beside him. Despite the shock, our sources say Michael wasted no time chasing the perpetrator down the street ... that is, until authorities arrived at the scene and were able to handle the rest.

The alleged assailant was identified as 27-year-old Xavier Israel ... with a witness claiming they observed him picking up a rock and hurling it at Michael to corroborate the account of the incident.

Police say Xavier was taken into custody without incident and has been booked for assault.