Three fire engines and around 15 firefighters were called to a fire at a house on Villiers Road in Willesden.
A small decking area on a first floor balcony of a three storey house was destroyed by fire and part of a bedroom on the first floor was also damaged by the blaze. Three people were treated on scene after suffering from smoke inhalation.
The Brigade was called at 0557 and the fire was under control by 0622. Fire crews from Willesden, West Hampstead and North Kensington fire station.
The cause of the fire is under investigation.