FREDERICK, Md. (AP) — Police in Maryland are investigating the death of a man who had been taken into custody after acting erratically.

The Frederick Police Department said Thursday that officers encountered the man shortly before 3 a.m. Monday. They had gotten a report of a man causing a disturbance.

Police said they suspected he was on drugs. He fled from police, but officers were eventually able to detain him for a medical evaluation.

Police said the man became unresponsive as they prepared to take him to a hospital. Attempts to save his life were made in the ambulance and later at the hospital, where he died.

Because he had been in contact with police before his death, Frederick’s police department said it asked the Montgomery County Police Department to conduct an independent investigation.