The elderly man was taken to hospital and was expected to survive, Bowser said, adding the man was found by a team assessing the damage to the building.

The man was believed to have been trapped inside his apartment within the housing complex during the fire last week, and shouted when he heard investigators outside his door on Monday.

“The resident was found by crews hired by the building owners to evaluate the safety of the structure,” Bowser said.

“It appears that, based on the report that I got from the building workers, that he was sitting in his apartment.”

Washington fire chief Gregory Dean said the fire crews who initially checked for seniors left behind in the housing complex “may have missed the apartment” in the chaos of the evacuation.

The mayor announced an investigation into the incident, adding that further sweeps of the building would take place. DM