Gallons of hydrochloric acid have leaked in the grounds of a Bedfordshire vehicle firm.
Between four and 10 gallons (18 to 82 litres) leaked from the boiler house at IBC Vehicles in Kimpton Road, Luton, a fire service spokeswoman said.
Crews were called at 1533 BST and two firefighters in airtight suits went into the building to stem the leak.
The Environment Agency stopped the acid getting into drains. The site will be cleaned by specialist staff.
Bedfordshire and Luton Fire Service group commander Chris Adams said: "The acid was in a tank which was protected by a wall to prevent any spread of spillage.
"The incident was dealt with swiftly and professionally by the teams on site."