Four fire engines and 21 firefighters and officers were called to a flat fire in Kilburn this afternoon.
The blaze broke out at a first floor flat in a fire-storey block of flats in Kilburn Priory.
One woman was rescued by firefighters wearing breathing apparatus and she was taken to hospital, where she sadly later died.
Another adult and a child left a neighbouring flat before the Brigade arrived.
London Fire Brigade control officers gave fire survival guidance to a resident in the block who was advised to stay where there is fresh air and stay out of smoke logged areas.
All other residents were advised to stay inside their flats while firefighters tackled the blaze.
Station manager Jerome Kumedzina, who was at the scene, said: “If there is a fire elsewhere in the building but not inside your home you're usually safer staying in your flat unless heat or smoke is affecting you.
"Flats and maisonettes are built to give you some protection from fire – a minimum of 30 minutes and up to 60. Walls, floors and doors will hold back flames and smoke for a time.
"If you leave your flat you could be rushing into choking smoke, the fire itself or firefighters using equipment to bring the fire under control in another part of the building.
“Living in a flat is not more dangerous than living in a house, but it's important to know that your fire plan should be different.”
Half of the flat involved in the blaze was damaged by fire.
Crews from West Hampstead, Paddington, North Kensington and Willesden fire stations attended the scene.
The Brigade was called at 1438 and the fire was under control by 1607.
The cause of the fire is under investigation.