Four fire engines and around 25 firefighters were called to a fire at a house on Connaught Road in Barnet.
The whole of the ground floor and first floor of the two storey semi-detached house were destroyed by fire. Sadly firefighters found the body of a woman inside the property. She was pronounced dead at the scene.
One man left the property before the Brigade arrived and was taken to hospital by London Ambulance Service and treated for smoke inhalation.
The Brigade's 999 Control centre received 18 calls alerting them to the fire.
The Brigade was called at 1120 and the incident was under control by 1253. Fire crews from Southgate and Hornsey fire stations attended alongside colleagues from Hertfordshire Fire and Rescue service.
The cause of the fire is under investigation.