A FIRE that ripped through a Blackburn factory was caused by a gang of teen arsonists, police have revealed.

Now officers are looking to track down the firestarters who were seen running away from the former Davies Pet Meats factory.

Police launched an investigation with Lancashire Fire and Rescue after 45 firefighters were drafted in to battle the blaze at 9pm on Friday.

Crews from Blackburn, Accrington and Great Harwood, as well as specialist units from Burnley and Preston, spent two hours fight the fire to stop it spreading through the disused, single-storey building.

Inspector Steve Haworth, of Blackburn Police, said: "We are treating the fire as arson.

"A group of about five or six teenage lads were seen running away from the fire as patrols and the fire brigade were arriving.

"We do have one or two suspects but if anyone can provide us with further information, that may help us and we would be grateful."

Sub-officer Tony Ashworth, from Blackburn Fire and Rescue, said: "We saw the big plume of black smoke as we were driving to the incident.

"An off-duty firefighter rang it in and he said the flames were coming out of the roof so we were able to get the aerial platform ladder there a lot quicker than we would normally, which helped us a great deal.

"It was an L-shaped building and 25 per cent of it was already well alight when we arrived.

"We sent for six more fire engines to help us to stop the fire from spreading further.

"Twelve firefighters wearing breathing apparatus went inside the building and used water jets to tackle it from there. We basically surrounded the building from all angles.

"We also had the environmental unit there because the building was close to the canal and we didn't want water from the fire going into it and contaminating the canal."

Anyone with information about the fire should call Blackburn Police on 01254 51212 or the confidential Crimestoppers hotline on 0800 555 111.