Four fire engines and 25 firefighters were called to a fire at a flat on South Road in Southall.
A ground floor flat was completely destroyed by fire. Three residents were led to safety by crews wearing breathing apparatus. Another two people left before the Brigade arrived. One woman was treated on scene for smoke inhalation by London Ambulance Service.
The Brigade's 999 Control centre received their first call alerting them to the fire at 2152 and the incident was over by 2253. Fire crews from Southall, Ealing and Hayes fire stations were in attendance.
The cause of the fire is under investigation by the Met police and the Brigade's fire investigation team.