A woman sadly died in a suspected gas explosion at a flat on Fulbeck Way, Harrow.
Ten fire engines and around 70 firefighters were called to the scene.
The first floor partially collapsed due to the force of the explosion.
Firefighters using an aerial ladder platform and breathing apparatus rescued a man, woman, and a baby from the first floor. The woman and baby were assessed at the scene and taken to hospital by London Ambulance Service crews.
A 20 metre cordon has been put in place and around 40 people from neighbouring properties have been evacuated as a precaution.
The Brigade was called at 0057 and the fire was under control at 0333. Fire crews from Harrow, Northolt, Stanmore and surrounding fire stations attended the incident and are expected to remain at the scene to dampen down.
The cause of the explosion is not known at this time but a gas explosion is suspected and is being investigated by the Brigade and the Metropolitan Police Service.