At least one house in Kensal Rise, in the north-west of the capital, had its side pulled off by the freak 30-second twister, while trees were also knocked down.

Eyewitness James Miles told Sky News television that the sky went dark and there was thunder and lightning immediately before the tornado struck.

Describing the event, he said: "Everything just goes round and round for about 20 seconds until it skips over you and then all of a sudden it's silent and then the debris is all over the place."

Police and paramedics rushed to the scene, but there were no immediate reports of injuries.

"I think a lot of people are shaken up because it's not the sort of thing that would happen in the centre of London," said Miles. "It's global warming I suppose, isn't it?" he added.

Another eyewitness, Sally Johnson, said she thought she was going to die. "All the cars and the windows, everything (was) smashed in," she told Sky. "There's debris everywhere, you can hardly walk."