A worker suffered burns over 70-percent of his body in a small blast and fire at a New York-Presbyterian/Columbia hospital medical school plant in Washington Heights on Friday morning, officials said.

A Fire Department spokesman said the small flash fire occurred at at 9:44 a.m. at 650 West 168th Street in Manhattan, on a 22nd-floor room.

There, workers were cleaning pipes leading to a domestic hot water tank in a mechanical room, when, suddenly there was a, “little bit of an explosion and a flash fire,” the spokesman said.

More specifically, as the workers cleaned the pipes with some kind of cleaning solution, someone turned on a halogen lamp and the vapors from the cleaning solution interacted, causing the fire, the spokesman said.

The most seriously injured worker suffered burns on 70 percent of his body. A second worker injured his arms and hands when he tried to pull the first man out of the tank. A third person suffered respiratory injuries, the spokesman said.

Emergency responders initially sought to bring the injured men to the burn unit at New York-Presbyterian/Weill Cornell hospital, on the east side of Manhattan, the police said.

But as they were en-route, the most seriously injured man appeared to be taking a, “turn for the worst,” an official said, so the emergency crew pulled into Harlem Hospital for more immediate emergency treatment.

The incident, apparently accidental, did not disrupt hospital operations, said Paul J. Browne, the police department’s chief spokesman. It appears there is, “no criminality in this incident,” Mr. Browne said.