Four fire engines and 21 firefighters and officers were called to a roof fire on Saint Stephens Road in West Drayton yesterday evening.
Part of the roof of a four storey block containing shops and flats were damaged by the blaze.
Around 10 people left the property before the arrival of the Brigade, and further 30 were evacuated from the third and fourth floors by fire crews wearing breathing apparatus.
The Brigade was called at 1955 and the fire was under control by 2055. Fire crews from Hillingdon, Heathrow and Hendon fire stations attended the scene. The cause of the fire is under investigation.