Boston firefighters responded to a Level 2 danger situation at Tufts University School of Medicine on Harrison Avenue on Tuesday afternoon.
Firefighters have reportedly investigated an unknown haze on the seventh floor. The first call arrived around 4 p.m.
There are no illnesses to report, firefighters said.
The problem was caused by a fire in an in-room refrigerator, which was sealed. Firefighters said there was no danger.
The air quality in the building has been checked and found to be safe. The building was evacuated as a precaution.
Hazardous Materials Specialists will remain on site while an environmental cleanup company oversees the cleanup.
No further information was immediately available.