BANGOR — A malfunctioning fan prompted the temporary evacuation Tuesday of three floors of offices at St. Joseph Hospital.

Firefighters were called to the hospital at 11:06 a.m. to investigate reports of smoky haze and an unusual odor in an office wing on the Broadway side of the hospital, according to Bangor Assistant Fire Chief Vance Tripp.

After the offices were evacuated, firefighters using thermal-imaging equipment pinpointed the problem to a faulty fan that was part of the air-exchange system on the first floor of offices.

The malfunction resulted in a buildup of heat near the chimney, with temperatures reaching 120 degrees, Tripp said. The built-up temperatures required fire crews to cut a hole into the wall for ventilation. The fan has since been repaired, he added.

Hospital spokesman Kathy Jeffrey said the rest of the hospital was unaffected by the incident.

“This has not affected patient care at all,” said Jeffrey. She said that during the evacuation, occupants of the affected offices were dispersed throughout the rest of the hospital, including the emergency room, where some of the physicians whose offices had to be vacated continued to see patients.

The office wing reopened at 1 p.m., Jeffrey said.

Tripp said that hospital security and maintenance personnel oversaw the evacuation.

“All hands did a fine job,” Tripp said.

Tripp said that 20 firefighters, three fire engines and three ambulances responded.