The Cambridge fire department swiftly knocked down a smoky rooftop fire at 1 Main St. near Kendall Square, a fire official said.
Cambridge firefighters responded to the call at about noon on the top floor of the 14-story office building. By 12:10 p.m. the fire had been knocked down, Assistant Fire Chief James Burns said in a telephone interview.
Black smoke could be seen billowing from the high-rise building for miles. Local TV station helicopter footage showed firefighters on the roof of the building, where the smoke appeared to be coming out of a cooling unit.
The Oracle University Training Centre and the MIT Technology Review magazine are among the tenants in the building.
A cause has not yet been determined, said Burns.