A blaze at a goods yard which ran underneath an electricity line has caused almost 90,000 properties to be without power.
A huge plume of smoke loomed over the yard on Wharf Street, Canning Town, east London, as 60 firefighters attempted to put out the fire.
London Fire Brigade said 12 fire engines are at the scene where a warehouse, a pallet yard and a scrapyard are alight.
The fire, which started at 3pm on Thursday, is close to a diesel tank which has not yet been affected by the blaze, a spokesman added.
UK Power Networks said that the power was restored to all customers within an hour and 10 minutes.
A spokesman said: "We apologise to customers in east London who suffered a power cut today when a fire in Canning Town, which was not on our equipment, damaged overhead power lines."
Transport for London (TfL) said that the A13 is closed in both directions at Canning Town but that Tube and Docklands Light Railway services in the area are operating as normal.
UK Power Networks said the power cut also led to the temporary closure of Archway, Arsenal, Caledonian Road and Tufnell Park Tube stations.
A TfL spokesman said trains continued to operate through the area and all stations have since reopened.