MILWAUKEE - Milwaukee fire crews had to evacuate the U.S. Cellular Arena Sunday morning during Marquette University's December commencement ceremony.

“A small motor in one of the air circulation units had shut down," said Richard A. Geyer, President and CEO of the Wisconsin Center District. "We have taken this unit out of service and will replace the motor on Monday. The U.S. Cellular Arena has been ventilated, and we’re at normal operations.  We always take additional precautionary measures when we have people in our buildings. I’m glad that our technicians were on top of it and that everyone was safe.”

Smoke in the building forced the evacuation of 3,000 people.

A witness says that as Fr. Robert Wild, S.J. was giving his final remarks, a smoky smell came across the arena, so most people were on their way out of the area.

The witness said Milwaukee firefighters arrived as people were filing out of the arena.

There is no structural damage, and the arena is safe for use.