An electrical problem  in an elevators in the University of Hawaii-Manoa’s Webster Hall was the source of heavy smoke that sent nine fire companies and 35 firefighters to a lecture hall early Thursday morning, officials said.

The elevator is out of service and is being repaired, UH-Manoa officials said. No classes were cancelled.

Webster is home to the School of Nursing, but classes from other disciplines are also held in the building.

Despite using thermal imaging cameras, fire crews could not locate the origin of the smoke.

University security reported they saw heavy smoke coming from the second floor of the building at 1:04 a.m.