Gregory said the Chapel Hill Fire Department and UNC Environment, Health and Safety officials are investigating.
People in Dey Hall just before 4 p.m. said they heard a loud noise and the lights went out. About five minutes later, fire alarms went off.
Around the same time, power went out across central campus, including main gathering spots such as Lenoir Dining Hall, the Student Union, Davis Library, the Undergraduate Library, Student Stores and the Campus Y.
Residence halls close to Polk Place and some classroom buildings also lost power.
Power was restored in every campus building except Wilson Library and Dey Hall at about 7 p.m. Lenoir Dining Hall, Davis Library and the Undergraduate Library all closed overnight after they lost power.
Wilson Library and Dey Hall still do not have power, according to Alert Carolina. Classes beginning before noon in those two buildings have been canceled, and employees working there are asked not to come to work until the power comes back on. There was no expected time given in the Alert Carolina for when the power would come back in those buildings.
Power returned in time for students to avoid plans discussed in a Department of Housing and Residential Education email, which said students wouldn’t be allowed to stay in dorms without power.
The email, which was sent at 6:20 p.m., said life-safety equipment, such as sprinklers, was affected by the power outage, so students could not stay overnight in the buildings.