Five fire engines and around 30 firefighters tackled a fire at a block of flats on Manchester Road in Millwall.
Half of a four roomed maisonette split between the second and third floor was damaged by the fire. One man was taken to hospital by London Ambulance Service. Two people left the building before the Brigade arrived.
Control Officers took the first of two calls at 0534 and mobilised crews from Millwall, Poplar, Plaistow and surrounding fire stations to the scene. The fire was extinguished by 0648.
The cause of the fire is under investigation.