Five fire engines and around 30 firefighters tackled a fire at a shop with dwellings above on Longfield Avenue in Ealing.
A sauna room on the first floor of the nine-storey building was partially damaged by fire. Around 13 people left the building before the arrival of the Brigade. There are no reports of any injuries.
The fire is believed to have been accidental and caused by an electrical fault in a sauna control panel.
The Brigade was called at 1224 and the fire was under control by 1400. Crews from Acton, Southall and Wembley fire stations attended the scene.