A fire which broke out in Wembley is thought to have been started by a cannabis farm in the building’s basement.

Four fire engines and 21 firefighters and officers were called to the blaze in Preston Road on Saturday night.

Ten people were evacuated from the building before teams from Wembley and Stanmore fire stations arrived at 8pm.

Philip Bromberg, chairman of Preston Library in nearby Carlton Avenue East, was alerted to the fire when their film night was interrupted by a black out.

He went outside to check the fuse box and saw four fire engines battling the flames.

Unable to close the electronic shutters to secure the building and leave, he and two volunteers stayed at the premises until 1am before power was restored.

He said: “We can’t close our shutters manually so we had to wait while they sorted out the fire. They cut their way into the building and later I spoke to a guy from the UK Power Network. He said there had been a cannabis farm in the basement of the shop.

“Cannabis farms do catch fire easily. The plants grow in enclosed spaces under intensive lighting, it’s not actually that unusual.”

The fire services have confirmed they are investigating the cause of the fire with the police.

The police have been contacted.