Investigators have found that a blaze that filled Bradford's skyline with thick black smoke yesterday was accidental.

Seventy firefighters tackled the huge fire at Cuckoo Nest industrial estate in Norcroft Street, Listerhills, Bradford, which broke out shortly before 11.30am.

A 200-metre cordon was set-up and 30 people were forced to leave neighbouring businesses as potentially explosive cylinders were found in the burning car repair garage.

An investigation by West Yorkshire Fire and Rescue Service concluded the cause of the fire was accidental. It is believed to be linked to welding operations.

Firefighters said they were initially called to reports of a car fire at 11.30am yesterday, but found the single-storey building was alight when they arrived.

The roof was destroyed, leaving leaving just a frame, but firefighters from 14 stations managed to stop it spreading.

District Commander for Bradford, Martin Speed, said: “The fire was discovered by mechanics working within the garage who then raised the alarm.

"Before the fire service’s arrival they attempted to put the fire out using hand-held extinguishers but were unable to do so. Fortunately no-one was hurt.

"On our arrival workers were also attempting to remove vehicles from the site, however, a handful of cars have been destroyed by fire."

Nick Smith, senior operations manager for West Yorkshire Fire and Rescue Service, said fire crews had surrounded the blaze by about 12.30pm.

"There are lots of different units with various uses in one building," said Mr Smith. "There's a spray shop, catering facilities, garages."

No-one was injured in the fire, which sent plumes of smoke blowing through the air towards Canal Road.

Hundreds of people gathered near the scene of the fire, with many less than 100 yards from the blaze at one stage before the police moved them back to the cordon.

The owner of one of the units was too upset to speak, said one of his friends.

Another man said: "It just seemed to come out of nowhere. Suddenly there was smoke everywhere."

One added: "I can't believe how much smoke there is. I'm glad no-one is hurt."

It took two hours to get the fire under control and by 2pm yesterday afternoon crews were damping down.

DC Speed added: “The smoke from this fire could be seen for miles around, however, our crews have worked quickly to get the blaze under control and prevent further spreading.”

Firefighters were expected to remain overnight at the site overnight and one fire engine remained at the scene this morning.