A top official at Tufts University in Medford said a bomb threat found on campus made reference to a labor dispute involving the school's janitors.
Tufts Senior Vice President Mary Jeka said the threat found taped to the door of campus health services Monday morning remains under investigation.
Students were told to stay in their dorms, final exams were postponed and all non-essential staff was sent home.
The university in Medford and Somerville closed several buildings referenced in the note, which was found near where a car was found burning.
The university said in a statement that the buildings were evacuated and "multiple law enforcement agencies are actively working to clear" them.
A decision on afternoon exams and activities has not yet been made. Classes have ended for the semester.