At least 60 firefighters are battling a huge blaze at a block of flats in north London. The fire service said the blaze has engulfed the second and third storeys, and the roof of the four-storey block of flats. A picture tweeted by the London Fire Brigade showed a crane above a building in flames. The block is on Daleham Gardens in Hampstead. Around 20 people were forced to flee their homes before firefighters arrived. London Fire Brigade said in a statement: "Eight fire engines and around 60 firefighters and officers were called to a fire in a block of flats on Daleham Gardens in Hampstead during the early hours of this morning. "An aerial appliance is also being used to help fight the fire. "The fire is affecting the second and third floors of the four storey building, as well as its roof. "Around 20 people left the building before the Brigade arrived. "Motorists are being advised to avoid the area while crews deal with the incident. "The Brigade was called at 0152. "Crews from West Hampstead, Kentish Town, Euston, .Paddington and Holloway fire stations are at the scene. "The cause of the fire is not known at this stage."