Twenty fire engines and around 125 firefighters are tackling a blaze at a warehouse in Barking, east London.
Officers from the London Fire Brigade (LFB) were called to the single-storey warehouse on Alfreds Way on Friday evening after reports of a building being alight.
Fire crews from Barking, East Ham, Dagenham, Plaistow, Ilford and surrounding fire stations also attended the scene.
They were supported by members of the London Ambulance Service (LAS), who urged people living in the area to keep windows and doors shut due to the large amounts of smoke being emitted by the blaze.
A spokesman for the LAS said that an ambulance crew, an incident response officer and a hazardous area response team had been dispatched but that no-one had yet been treated at the scene.
The LFB said the cause of the fire is not known at this stage.