CHICAGO (CBS) — A man was found dead in an apartment fire Thursday morning in the South Side Englewood neighborhood.

Chicago Fire Department Chief Juan Hernandez said crews were called to the building, in the 6800 block of South Normal, shortly after 2 a.m. The fire was put out a short time later.

“They found fire on the second floor, contained to one room,” Hernandez said. “They put out the fire and found a 51-year-old male, unconscious.”

The man was taken to a nearby hospital and pronounced dead. His cause of death is unknown. No one else was injured and Hernandez said functioning smoke detectors could be the reason why.

“They possibly alerted other people in the building of the fire.”

The cause of the fire remains under investigation.

“They cannot rule out the use of smoking materials,” Hernandez said. “That means there’s a possibility that smoking materials caused this fire.”

Two adults were displaced by the fire, Hernandez said.

The police Bomb and Arson Unit was investigating, although the fire appeared to be “noncriminal in nature,” police said.

(CBS Chicago and the Sun-Times Media Wire contributed to this copy. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)