Two cyclists on the same bike have been taken to hospital after colliding with a bus in Uxbridge Road in Ealing Common.
Police have closed a short stretch of the road heading east, just off Hanger Lane.
Road cameras show several ambulances on the scene and police have taped off the short section of road, according to The AA Travel.
Metropolitan Police told GetWestLondon two people were taken to hospital, although their conditions are not believed to be life-threatening.
The 207, 427 and 607 buses have all been forced to reroute.
Travel service Inrix says drivers are squeezing by to use Hanger Lane, where traffic is relatively slow heading south.
Road users are advised to avoid the area where possible.
Follow developments from the scene on our live blog here .