Chicago, IL – A 70-year-old man was found dead in a Hyde Park apartment unit Tuesday night after the Chicago Fire Department responded to a carbon monoxide alarm, authorities said.

An alarm went off about 9:20 p.m. inside an apartment building in the 800 block of East 53rd Street, according to Chicago police. Peoples Gas and the Chicago Fire Department responded. While clearing the building, CFD found a unit with a stove turned on, which caused the alarm to sound.

Across the hall in a separate unit, the man was found unresponsive, police said. Preliminary information suggests he died of carbon monoxide poisoning, but the Cook County medical examiner’s office will determine the official cause of death.

Fire Department Deputy District Chief Curtis Hudson identified the man as 70 years old. His name has not been released.