Four fire engines and around 25 firefighters were called to a fire at a house on Hazelbury Lane in Edmonton.
The first floor of the semi-detached property was destroyed by the fire. Two men and two women left the building before the Brigade arrived. They were assessed at the scene by London Ambulance Service crews.
Firefighter Sean Middleton, who was at the scene, said: "Crews were faced with a well developed fire on arrival, with flames coming out of both the first floor windows.
"It was quite windy which was also contributing to the smoke spread.
"Crews worked hard to bring the fire under control and were able to stop it spreading to the adjoining property via the loft and roof space."
The Brigade was called at 2242 and the fire was under control by 2358. Fire crews from Edmonton, Southgate and Enfield fire stations were at the scene.
The cause of the fire is under investigation.