Dozens of firefighters are battling a massive blaze near Oxford Circus in central London, with photos posted online showing a huge cloud of smoke visible from across the capital.
At least 50 firefighters were on scene after the fire broke out at a building site in Great Portland Street at about 12.45pm.
A 25-metre (80ft) exclusion zone has been set up amid fears that gas cylinders inside the building could explode.
More than 40 calls were placed to 999 as smoke poured out of the building, next to the BBC's London headquarters.
BBC employees told on Twitter how the blaze started in a new development next to Broadcasting House and the London Fire Brigade responded quickly.