Firefighters were called to reports of a van alight on Ruskin Avenue in Feltham.
A van was destroyed by fire. One gas cylinder which was involved in the fire exploded and crews removed and cooled three further gas cylinders to an ambient temperature. Three people were treated on scene by London Ambulance Service crews and two people were taken to hospital.
A London Fire Brigade spokesperson said: "Fires involving gas cylinders are particularly dangerous as some cylinders can explode when exposed to heat. A 25-metre cordon was put in place as a precaution whilst crews worked to make the scene safe. Thankfully, it appears that nobody was seriously hurt.
"Make sure any gas cylinders are appropriately signposted and stored safely and securely, ensuring that they won't fall over."
The Brigade was called at 0719 and the fire was under control by 0831. Four fire engines and around 25 firefighters from Feltham and Heston fire stations attended the scene.
The cause of the fire is under investigation.