Crews were called to the Graphic Packaging plant a little after 1 p.m. Saturday. That's near Bridge St. and 1st Ave. in Wausau.
The plant lost power after a pump motor caught on fire, causing a lot of heat and smoke buildup.
The plant was not in full operation, and only maintenance crews were in the building at the time.
"The fire was extinguished rather quickly, but there's significant damage to the motor. The pump will need repair," says Capt. Doug Beula of the Wausau Fire Department.
There's no word yet on how much the damage will cost the company.