A Chicago police captain died while on duty early Sunday morning.

The officer,  50-year-old James Lavoy was found unresponsive in his squad car on I-94. Police said there were no signs of trauma and believe it may have been cardiac related. He was taken to the hospital, where he was pronounced dead. Captain Lavoy was a Calumet district supervisor.

As an ambulance took his body to the medical examiner’s office, dozens of squad cars honored him in an end-of-watch procession. A death investigation is underway.