The fire started at about 8:50 p.m. Sunday at Nan Ya Plastics on U.S. 59 near FM 102, according to the Wharton Police Department.
Video from the scene showed flames shooting out of the building.
"There's going to be employees in the building still. They're evacuating now," an emergency responder could be heard reporting on a radio call. "On location Wharton, we do have flames showing."
On Facebook, officials said all staff and personnel had been accounted for.
No injuries were reported.
Officials plan on releasing an update on exactly what happened sometime Monday.