TULSA, Oklahoma - An inmate at the Tulsa County Jail died of an apparent cardiac arrest, the Tulsa County Sheriff's Office announced Monday.

Major Shannon Clark of TCSO says Victor Lamont Smittick was found unresponsive in his housing unit Sunday afternoon. A detention officer making a security check discovered the 56-year-old man.

Jail medics were on scene in seconds and "began administering aggressive life-saving procedures," Clark said in a new bulletin. EMSA and Tulsa firefighters joined in the life-saving attempts but Smittick was pronounced dead at OSU Medical Center early Sunday evening.

Smittick had been recently released from St. John Hospital for heart-related problems and appears to have died of natural causes, Clark said.

He was arrested at about 10:15 p.m. Saturday on a complaint of actual physical control.

The Oklahoma Medical Examiner has taken custody of the body to determine cause of death.