Four fire engines and around 25 firefighters were called to a takeaway shop fire on Bath Road in Hounslow.
Part of the ground floor of a mid-terraced takeaway shop with flats above was damaged by fire and smoke logging affected adjacent properties. Three people left the building before the Brigade arrived. There were no reports of any injuries.
The fire is believed to have been accidental and caused by cooking oil igniting in an unattended pan, which then set alight to oil residue in the extraction system.
A London Fire Brigade spokesperson said: "The alarm was raised by a member of the public who saw smoke coming from the takeaway shop. When crews arrived at the scene they located the fire in the extraction system above the cooker.
"We'd like to remind restaurant and takeaway owners to ensure they don't have dirty ducting. If you don't clean the ducting in your extraction system regularly, you're at a greater risk of ducting fires.
"You should also make sure you keep the hob, cooker hood and extractor fan clean too – built up fat and grease can ignite and cause a fire."
The Brigade was called at 1333 and the fire was under control by 1506. Fire crews from Feltham and Heston fire stations attended the scene.