More than 70 firefighters tackled a huge blaze at a block of flats in Bethnal Green.
Ten fire engines and 72 officers were sent to the scene in Turin Street on Saturday afternoon.
Thick black smoke poured into the sky as firefighters fought the blaze which broke out in a third floor flat.
Paramedics took one man to hospital who was suffering from smoke inhalation.
Images and video footage showed bright flames billowing from the roof.
London Fire Brigade said the whole of the third floor and the roof are alight.
One image shared on social media shows the entirety of the roof destroyed.
Fire broke out in Dickinson House, Turin Street. Firefighters trying to stop the fire. pic.twitter.com/xuljxPc00t— abdul mukit (@mukitmbe) June 24, 2017
And one horrified bystander tweeted: "The fire has spread to the rooftop of the flat in Bethnal Green Turin Street! Hope everyone is ok."
A spokeswoman said: "The Brigade was called at 4.25pm. Firefighters from Bethnal Green and surrounding fire stations are attending the scene.
"The cause of the fire is not known at this stage."
Bethnal Green Road was closed both ways between Satchwell Road and Turin street a fire crews from surrounding fire stations tackled the blaze,
The fire was under control by 7.30pm.