Commercial Partitioning Contractor
The fire service was called to AAC Cyroma Ltd, on the Beaumont Road Industrial Estate in Banbury, at 22:02 BST on Wednesday.
It took crews two hours to bring the blaze. Fifteen people who had been in the building were helped to safety.
Group manager Pete Graham called it a "serious incident". The fire service stayed on site through the night.
Firefighters had to wear protective chemical clothing when entering the premises.
Mr Graham added: "The preplanning carried out by the site's management, and the fire protection measures and procedures in place, ensured the safety of their staff as well as assisting our firefighters in tackling this serious incident.
"The sprinkler system made a significant difference and prevented the fire developing significantly and enabled us to concentrate on dealing with the potential chemical issues."