Firefighters were first called to Action Manufacturing Company on the 500 block of Bailey Crossroad in West Fallowfield Township just after 3 a.m.
The Chester County Hazmat team also responded to the scene and determined that the safest course of action was to monitor the fire until it burned out on its own.
Action News has been told that all employees have been evacuated.
Crews remain on scene to investigate the cause.
Authorities in Chester County stress that there is no danger to the public.