Three men have been taken to hospital - one with serious burns - after a gas cylinder exploded at an industrial premises.
The incident happened in Brislington, Bristol, at a gas depot as an employee attempted to cap a cylinder.
Great Western Ambulance Service (GWAS) said it received a 999 call at 2.45pm on Thursday reporting that a single acetylene canister had exploded at the site in Whitby Road.
A man, reported to be in his 50s, was apparently capping the bottle at the time. He suffered extensive burns to his groin, arms and face and was taken to Frenchay Hospital.
Two other men, in their 40s or 50s, have been taken to the Bristol Royal Infirmary with less serious injuries. One has minor burns to his neck and the other was complaining of hearing problems.
Avon Fire and Rescue said the cylinder exploded inside a warehouse, which is owned by BOC gas, and that the fire was contained by the internal sprinkler system.
A 200 metre cordon was put in place as a precaution. Trains between Bristol Temple Meads station and Bath Spa were suspended as the line runs through the exclusion zone.
Surrounding industrial units were evacuated soon after the incident along with the nearby Avon Meads Retail Park and people were asked to avoid the area.
A spokesman for First Great Western said they had turned trains heading from Bath Spa to Bristol Temple Meads back to Bath and put on a replacement bus service. There was also a shuttle bus taking passengers between Bath and Chippenham and Swindon. Other services were diverted to Bristol Parkway station.
Catherine Mules, a GWAS paramedic who was first on scene, said: "This clearly had the potential to be a serious incident. We were given an early reassurance via our control room that there was no risk of further explosions, so we were able to concentrate on assessing and treating the patients straight away."