A large fire on an industrial estate in Kidderminster, Worcestershire, has been brought under control.
Flames were seen coming from a fibreglass factory, on the Hoobrook Industrial Estate, at about 13:45 BST.
A total of 10 fire crews along with police and ambulance personnel went to the scene.
Witnesses reported seeing "lots of thick black smoke" coming from a building at the back of a scrapyard on the industrial estate.
Smoke was seen billowing across the A449, where traffic started to build up.
Police set up a 200m exclusion zone because one of the units on fire contained gas bottles used for welding.
They were also concerned about asbestos in the fabric of the building.
It is not thought anyone was injured.
Diversions were put in place on surrounding roads.
Eyewitnesses reported hearing a "massive explosion" before seeing flames shoot 20ft into the air.
Group commander Mick Cadman, from Hereford and Worcester Fire Service, said at about 17:00 BST only the road onto the industrial estate was closed and workers at the site had been allowed back in to collect personal possessions and vehicles.
He said a couple of cylinders had exploded but the rest had been recovered and made safe.
He added: "The other key issue is the danger to the environment."
He said they had worked with the Environment Agency to contain any contaminants on the site to stop them entering the environment. There was no risk to the public, he added.
The cause of the fire is not yet known and the fire service has launched an investigation with West Mercia Police.
Mr Cadman said fire crews would remain at the site overnight damping down.