MILFORD (AP) — A 31-year-old man died Sunday after being found unresponsive in a Connecticut police department holding cell, hours after he was arrested following a traffic stop and brought to a hospital for observation, authorities said.

Milford police said officers performed lifesaving measures on the man when he was found unresponsive at 5 a.m. He was brought to a local hospital and pronounced dead, officials said. His name has not been released.

State police have been called in to investigate.

Milford police said in a statement Sunday that they arrested the man during a traffic stop Saturday afternoon, when they learned there was a warrant for his arrest. Officials said the man showed signs of “medical distress" while he was being processed and he was brought to a hospital.

Medical staff at the hospital discharged the man about 11 p.m. after examining and observing him, and he was taken back to the police station, officials said.

Milford police said they monitored the man in his cell during his time at the police department.