Four fire engines and around 25 firefighters tackled a house fire on Queen's Gardens in Hounslow.
Part of the rear garden and the ground floor of a semi-detached house were damaged by fire. Part of the single-storey extension of a neighbouring property was also damaged by the blaze. Three people were taken to hospital by London Ambulance Service crews and a further two people were assessed on scene.
Two gas cylinders were involved in the fire and firefighters cooled them to an ambient temperature as some cylinders can explode when exposed to heat. A 25-metre cordon was in place as a precaution.
The Brigade was called at 1238 and the fire was under control by 1428. Fire crews from Feltham and Heston fire stations attended the scene.
The fire is believed to have been accidental and involved the use of a gas cylinder.