West Sussex Fire and Rescue Service were called to Gillmans Industrial Estate on Natts Lane in Billingshurst around 5am today (Monday, June 10).
Photos showed at least four fire engines at the scene.
A spokesperson for the fire service: "At 4.50am this morning we responded to a hazardous materials incident at an industrial building in Natts Lane, Billingshurst.
"Joint Fire Control sent fire engines from Billingshurst, Crawley, Horsham, Petworth, Worthing and Surrey Fire & Rescue Service to the scene, as well as a command support unit from Haywards Heath and an aerial ladder platform from Worthing.
"Upon arrival firefighters wearing breathing apparatus entered the premises to carry out investigations. The cause of the chemical reaction was located and firefighters isolated the issue.
"Sussex Police were also in attendance and officers assisted the fire service in setting up cordons to keep members of the public safe.
"Fortunately there were no casualties and extensive checks were carried out to ensure the building was safe, before the incident was handed over to the occupiers."
Fire crews left the scene at around 7.40am.

1. Industrial estate fire
West Sussex Fire and Rescue Service were called to Gillmans Industrial Estate on Natts Lane in Billingshurst around 5am on Monday (June 10). Photo: Eddie Mitchell

2. Industrial estate fire
West Sussex Fire and Rescue Service were called to Gillmans Industrial Estate on Natts Lane in Billingshurst around 5am on Monday (June 10). Photo: Eddie Mitchell

3. Industrial estate fire
West Sussex Fire and Rescue Service were called to Gillmans Industrial Estate on Natts Lane in Billingshurst around 5am on Monday (June 10). Photo: Eddie Mitchell

4. Industrial estate fire
West Sussex Fire and Rescue Service were called to Gillmans Industrial Estate on Natts Lane in Billingshurst around 5am on Monday (June 10). Photo: Eddie Mitchell
