Firefighters are tackling a major fire at a County Durham factory.

Thick black smoke could be seen for miles after the blaze broke out at the Henderson plant, at Bowburn, near Durham City, at about 10am.

The factory makes garage doors and sliding door gear and, with 300 employees, is one of the area's major employers. Residents reported hearing explosions and flames were seen shooting out of the roof.

Ten fire appliances are at the scene, including an aerial ladder platform from Tyne and Wear. There are no reports of injuries.

"It is the biggest incident we have had so far this year,'' said Divisional Officer David Turnbull.

Police closed the A177 through Bowburn -- the main road between Durham City and the A1(M) -- and diverted traffic away from the village.