Explosions sent fireballs hundreds of feet into the air as flames swept an industrial chemical recycling plant Friday morning.
No injuries were reported and air monitoring had not picked up any hazardous chemicals about six hours later, but everyone within three-quarters of a mile (1,200 meters) of the plant was urged to evacuate, State Patrol spokesman Brent Pickard said at midday.
"The evacuation is precautionary," he said. "Right now there is no danger. The fire is still going on. They expect it to be an event that lasts all day and into the evening."
The blaze broke out around 6 a.m. at Waste Research and Reclamation, just south of Eau Claire, in western Wisconsin.
Subsequent explosions sent balls of fire more than 300 feet (91 meters) in the air, prompting firefighters to retreat from the site for several hours, Eau Claire County Sheriff Ron Cramer said.
The fire started in the plant's processing plant and triggered a boiler explosion, said Waste Research and Reclamation President Jim Hager. He said about 10 workers were just finishing the night shift and were unable to put out the flames with fire extinguishers.
"Everything I've heard indicated it started with electrical," Hager said.
He said the plant has chemicals that include flammable petroleum products and a variety of paint solvents.
The air monitors were checking for 300 different chemicals, Pickard said. He said experts believe what mostly was burning in the fire was alcohol, which he said should not cause significant environmental harm.