Two fire trucks and a rescue unit responded at 8:45 last night to a telephone call reporting smoke at 1780 Massachusetts Ave., across the street from Widener Gate.
Although six companies initially responded, no fire was found. A caller from the fifth floor of the office complex had phoned in the alarm but had left by the time firefighters appeared, according to a Cambridge Fire Department official on the scene.
About 20 people were evacuated from the building, but were permitted to reenter 15 minutes later.
Three companies responded to a fire alarm on the first floor of 20 DeWolfe St. at 9:45 p.m. According to the same Fire Department official, who was also on the scene, smoke odors were detected on the second and fourth floors of the dormitory, although no fire occurred. About 30 students were evacuated for 15 minutes.
No injures were reported in either incident.