Firefighters were called after a forklift truck fell onto a building on Chesterton Close in Greenford.
An industrial telehandler forklift truck had overturned onto a three-storey block maisonettes. One man from the affected maisonette was taken to hospital by London Ambulance Service crews. Another five people left the building uninjured.
Sub Officer Cam Bee, who was at the scene, said: "Crews arrived on scene to find that the large forklift had overturned and come to rest on a first floor window.
"Fortunately it had landed on a non-load bearing part of the building so damage to the maisonettes was limited to that area, rather than affecting the whole structure of the block.
"Crews made the scene safe and a 25m cordon was put in place as a precaution.
"This isn't an every day sort of job for firefighters and just goes to show the range of incidents our crews attend."
The Brigade was called at 1454 and the incident was over for firefighters by 1558. Three fire engines from Southall, Northolt and Park Royal were at the scene.