New York ? A fire at a major hospital sent smoke pouring through an emergency room Wednesday, injuring at least six firefighters and forcing 600 patients to be moved across the sprawling complex.

The fire began shortly before 6:30 p.m. in a second-floor mechanical room at the Mount Sinai Medical Center in Manhattan and spread to a first-floor emergency room, Fire Department spokesman Frank Dwyer said. The fire was confined to the mechanical room and the cause was not known.

Dwyer said patients were moved from the east wings to the west wings of the 12-story hospital, which has nearly 1,200 beds, as firefighters searched the building. The patients had been on the third through 11th floors.

There were no reports of injuries among patients.