Police are appealing for information and witnesses following a serious road traffic collision in Chiswick.
They were called at 5pm yesterday, with reports that a number of vehicles had collided with a male pedestrian on the Hogarth roundabout.
The man, as yet unidentified, has been taken to hospital where his condition is critical.
It is believed that all vehicles involved stopped at the scene.
Officers from the Collision Investigation Unit at Hampton are looking further into the incident.
Anyone with information should call 020 8941 9011