Ten fire engines and around 70 firefighters were called to a fire on Caledon Road in East Ham.
Part of the ground and first floors of a number of terraced houses converted into flats were damaged by the fire. Fencing and sheds in the rear of the properties were also destroyed. Eight people left the building before the Brigade arrived. One woman was treated at the scene by London Ambulance Service crews and taken to hospital.
Firefighters cooled and removed a propane cylinder as some cylinders can explode when exposed to heat.
Station Commander Keith Sanders, who was at the scene, said: "The fire affected a number of gardens and the back of some of the adjoining properties.
"Crews worked hard to bring the fire under control and prevent it from spreading further.
"There was heavy traffic in the area and we advised motorists to avoid the area where possible."
The Brigade's 999 Control Officers took 31 calls to the blaze. They were able to use 999Eye to live stream the fire from a smart phone to screens in the Control Room, allowing for greater visibility of the incident.
When a 999 call is received by the Brigade, the caller may be asked if they would like to provide a live video stream of the scene using their smartphone. The Control Officer will send a text message with a secure, one-time-use link that opens a live stream direct from the phone to the Control room. 999Eye provides better situational awareness and allows us to offer the best advice based on live footage.
The fire is believed to have been accidental and caused by a bonfire in a rear garden spreading out of control.
The Brigade was called at 1330 and the fire was under control by 1536. Fire crews from East Ham, Plaistow, Leytonstone, Poplar, Millwall, Dagenham and surrounding fire stations were at the scene.