A man has been taken to hospital after a spill of sulphuric acid at a Stibbington bio-fuel plant.
The spill happened at Pure Fuels in Cambridgeshire, at about 17:40 BST on Wednesday.
Police said there was believed to have been three casualties. The ambulance service said one man was taken to hospital after being treated for burns.
The Health and Safety Executive is investigating, and the plant described it as an "isolated incident".
The Pure Fuels spokesman said it "did not post a wider danger", and said he hoped the employee would be "back at work in the very near future".
Cambridgeshire Fire and Rescue Service said it found a "small amount of chemical" when firefighters arrived at the industrial premises on Old Great North Road.
The service said crews had returned to their stations after the area was made safe by 19:30.
The plant is near to the Nene Valley Railway heritage attraction at Wansford.
In November, one person was treated for minor injuries after what at the time was believed to be "a methanol explosion" at the plant.