A huge plume of black smoke is rising over east London from a large fire close to the site of the 2012 Olympic site.
The fire is in a disused bus depot and the London Fire Brigade says 15 appliances and 75 firefighters are at the scene.
Smoke is visible across LondonScotland Yard has said it was not believed to be related to terrorism.
Emma Brompton, who works for a film production company in Forest Gate, told Sky News she and work colleagues had run into the street.
"From our production office it's blackened the sky. There are a few sirens going off. It's blackened the sky. All you can see are the plumes of black smoke."
Another witness said he had not heard an explosion before seeing the smoke, which appeared to be caused by diesel fuel.
The centre of the fire is said to be a bus depot at Waterden Road on the site for the 2012 Olympics.
The fire brigade has reported no casualties.
The north London railway line has been closed between Dalston and Stratford because of the thick smoke above Hackney Wick station.
James O'Connor, who was operating a crane, told Sky News the smoke shot up suddenly.
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