Four fire engines and around 25 firefighters were called to a fire at a flat, which was being used as a cannabis factory, on Seven Sisters Road in Tottenham on Saturday.
Part of a split-level flat on the ground and first floor of the building was damaged by fire. Half of another split-level flat on the first and second floors of the building was also damaged by the blaze. One woman was treated on scene by London Ambulance Service crews.
Station Officer Peter Campbell, who was at the scene, said: “Firefighters worked quickly to gain access to the property and located the fire inside a wall cavity in the roof of a flat. The property was empty at the time.
“Due to the position of the fire, crews used specialist cutting equipment to gain access to the area where the roof joists are and ensure that the fire had been fully extinguished.
“Cannabis factory fires can be particularly dangerous because of the way criminals use unsafe wiring to illegally obtain electricity in order to grow the plants
"They're often in top floors or lofts which means when a fire takes hold it spreads, destroying roofs and damaging neighbouring buildings.
"Firefighters can also be exposed to risks when dealing with the fires because of bad wiring and very hot lamps, as well as traps at some of the properties.
"It's important that people know the key signs and inform the police so that they can act swiftly to prevent these dangerous fires from happening. Common signs to look out for include blocked off windows, visitors coming and going at strange hours of the day and lots of heat and condensation."
The Brigade was called at 2107 and the fire was under control by 2317. Fire crews from Tottenham and Stoke Newington fire stations attended the scene.
The cause of the fire is under investigation.