A plume of black smoke rose over Great Portland Street, after a building across the road from the BBC radio studios caught fire.
Firefighters were called to the scene at 12.22pm (April 17). A spokesman for the London Fire Brigade said the blaze started in the lift motor room of a building that was being refurbished.
"Four fire engines and 20 firefighters attended a fire at a building on Great Portland Street," said the service in a statement.
"It was very visible and we've taken 35 999 calls.
"The fire is in the lift motor room on the roof. The cause of the fire is not known at this stage."
BBC presenter Jeremy Vine tweeted a picture of the blaze.
The BBC's Broadcasting House is based in Great Portland Place, while radio stations Radio 2 and Radio 6 are based in Great Portland Street.