Four fire engines and around 25 firefighters were called to a fire at a flat on Oakley Square in Camden.
Part of a five roomed maisonette on the ground and first floors were damaged by fire. Firefighters wearing breathing apparatus rescued one woman from the ground floor. She was treated on scene by London Ambulance Service crews.
The Brigade was called at 1455 and the fire was under control by 1623. Fire crews from Euston, Kentish Town and Soho fire stations attended the scene.
The cause of the fire is under investigation.