Bystanders watch as D.C. firefighters try to extinguish a fire on Isherwood St. NE. (Ricky Carioti/The Washington Post)

A body was found in the wreckage of a condominium building that burned and collapsed in Northeast Washington on Wednesday, authorities said.

D.C. firefighters battled the blaze at the building, which housed four condominiums, for more than two hours.

Authorities said an apparent explosion inside the building blew out windows, sending window frames and shattered glass flying across the street.

D.C. Fire and EMS officials said the fire broke out just before 4 p.m. at a building in the 1600 block of Isherwood Street NE, on the eastern edge of Capitol Hill.

Nearby streets were closed for hours.

A D.C. firefighter works to extinguish the blaze. (Ricky Carioti/The Washington Post)

Officer Hugh Carew, a D.C. police spokesman, said authorities discovered one body inside the burned building but couldn’t complete their search because of the debris in the structure.

Throughout the evening, firefighters sprayed water onto the charred remains of the two-story, four-unit building.

At least two adjacent buildings also were damaged. The explosion ejected red bricks into an alley as the fire demolished the structure, leaving charred wooden beams and a collapsed roof and second floor.

Barbara Williams, 55, said she was standing in her driveway about 20 yards from the building when she heard a bang. Shattered glass began to fall on her and her car, she said.

“We heard the explosion, then we saw smoke and the back of the building was just gone,” Williams said.

Authorities said there was no immediate word on what might have caused the fire or explosion. Washington Gas was on the scene, but company spokesman Ruben E. Rodriguez said the utility did not provide service to the building.

As firefighters worked, authorities closed 16th and 17th streets between E and F streets. The fire was extinguished by 6:15 p.m.

As of 8 p.m., District and Red Cross authorities were trying to determine how many people lived in at least three damaged buildings and to account for their whereabouts.

Officials estimated that at least 10 units were affected, and the Red Cross was helping about 35 people.

Andrew Brown, 49, who lives in a ground-floor unit next door to the burned building, was not home when the explosion occurred.

As of 5:30 p.m., he was not able to get back into his home and wasn’t sure whether there was damage from the blast or water.

“I was lucky enough not to be home,” he said, “but I don’t know where I’m going to stay.”

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