It wasn't immediately known how many homes were evacuated in the western Arkansas town of 4,000, emergency management spokeswoman Renee Preslar said.
A hazardous materials team from Sebastian County was heading to Booneville, Preslar said
Meredith Voges, 22, of Connecticut, said she heard the explosion while staying at a hotel just behind the plant. Voges, a member of a film crew shooting footage for a television program about a Booneville school principal, said hotel staff and police urged everyone to leave the area.
"The whole factory was ablaze with black smoke flying into the air, plumes of smoke," Voges said.
Booneville is about 90 miles northwest of Little Rock.