A five-story apartment caught on fire Wednesday morning in the Dunning neighborhood on the Northwest Side, killing one man and leaving a woman severely injured.

At 3:46 a.m., a fire broke out at a building in the 6400 block of West Belle Plaine Avenue, according to the Chicago Fire Department. It was contained to one unit on the building’s fifth floor.

A woman and man were taken to Community First Medical Center in critical condition, CFD said.

The man, 88-year-old Radzislaw Sadzak, was pronounced dead later at 4:41 a.m., according to the Cook County medical examiner’s office. He lived in the same block.

An autopsy Thursday found Sadzak died of smoke inhalation and burns from the fire and his death was ruled an accident, the medical examiner’s office said.

Firefighters smothered the blaze by 4:45 a.m., CFD said. About 20 residents of the building were displaced.

CFD was investigating the cause of the fire.