Eight fire engines and around 60 firefighters tackled the blaze in Christchurch Avenue just after 12.30am today (September 4).
The fire was located in a semi-detached property of two floors, converted into flats.
Five people left the property before the brigade arrived, and all were taken to hospital by the London Ambulance Service.
Part of the first floor and the roof of the property were destroyed by the fire.
Control Officers mobilised crews from West Hampstead, Willesden, North Kensington and surrounding fire stations to the scene.
Firefighters had the incident under control just before 4am.
The cause of the fire is under investigation by the brigade.
We have contacted Metropolitan Police and London Ambulance Service for further information.
