Eight fire engines and around 60 firefighters were called to a fire at a block of maisonettes on Ealing Road in Brentford.
Half of a split-level maisonette on the ground and first floor of a seven-storey block was damaged by the fire. The fire spread to the external fascia of the building and part of a second floor maisonette and its balcony were also damaged. Around 30 people left the building before the Brigade arrived. One man was taken to hospital by London Ambulance Service crews.
The Brigade's 999 Control Officers took 31 calls to the blaze.
The Brigade's Fire Investigators believe the fire started when a disposable lighter used to light a candle was placed onto a bed.
Station Commander Jon Holt, who was at the scene, said: "Crews were faced with a fully developed fire upon arrival and worked hard to bring the blaze under control.
"It's really important that objects like lighters and matches are out and cold before disposing of them or putting them away.
"Preferably wet matches before throwing them into a bin. Never drop discarded lighters or matches on to materials that can easily catch fire, like bedding, and keep matches and lighters out of the reach of children."
The Brigade was called at 1042 and the fire was under control by 1157. Fire crews from Chiswick, Ealing, Heston, Acton, Richmond and surrounding fire stations were at the scene.