Three people are being treated in hospital following an explosion at a garage in Gloucester.
The fire service said the blast was believed to have been caused by fumes from an oxyacetylene tank igniting.
One man was airlifted to Bristol's Frenchay Hospital with serious burns. Two are being treated for minor burns.
The explosion happened at the Pullman Fleet Services garage on the Kingsway Business Park. The Health and Safety Executive has begun an investigation.
The garage where the incident happened is a subsidiary of the logistics firm Wincanton, carrying out vehicle repairs.
A statement from the company said: "All three employees are being treated in hospital and our immediate concerns are for them and their families.
"The Wincanton investigation team is on site and will be working with the authorities to investigate the cause of the explosion."
A Gloucestershire police spokesman said: "A 52-year-old man from Dymock has been taken by air ambulance to Frenchay where he is being treated for injuries described as 'life-changing'.
"Two men, a 33-year-old from Cinderford, and a 32-year-old from Innsworth, have been taken to Gloucestershire Royal Hospital with minor burns."