Candles left unattended are believed to be the cause of a flat fire on Birkbeck Road, Hornsey.
A man left the affected second floor flat uninjured before the arrival of the Brigade.
Station Manager Gary Wilson, who was at the scene, said:
"The fire is believed to have been caused by candles left unattended that caught bedding on fire. Candles are one of the most common causes of fire. It’s really important that you never leave a candle unattended and keep them away from curtains and anything else that can easily catch fire.
"Firefighters worked hard to bring the flat fire under control. A large amount of smoke was released into the corridor as the door to the affected flat was left open by the occupant which resulted in heavy smoke in the communal areas.
"A woman in a neighbouring flat was on the phone to our control and was receiving fire survival information. Firefighters quickly pitched a ladder and rescued her from the second floor. Fire crews wearing breathing apparatus rescued a further two people from the third floor via an internal staircase.
"Thirty people self evacuated from the building. A woman and a child were assessed at the scene and taken to hospital as a precaution by London Ambulance Service crews. Other residents stayed in their unaffected flats."
The Brigade's 999 Control Officers took 22 calls to the fire.
The Brigade was called at 2103 and the fire was under control at 2256. Around 40 firefighters from Hornsey, Holloway, Kentish Town, and Finchley attended the scene.