A pensioner suffered serious head injuries when he was hit by a car while on a Ruislip Road zebra crossing.
The 65-year-old was struck as he was crossing Ruislip Road, near the junction of Wayfarer Road, Northolt.
A 33-year-old staff member from the Happy Shopper at the scene saw the aftermath at about 12.40pm on Tuesday.
He said: "There was blood over the crossing and a man was sitting down in the island in the middle of the road.
"A workman digging up the road had called the ambulance as soon as it happened.
"There was blood on the man's head and he looked badly injured, a blue car had stopped a few yards away."
Ray Harrord, 60, who works as an administrator nearby, added: "A crowd of about 10 to 12 had gathered around. He was alive and sitting on the edge of the pavement.
"Police closed off the road and didn't reopen it again until about 4.45pm."
The London Ambulance Service said the victim was fully conscious and breathing but was taken to Hillingdon Hospital as a priority. His injuries were not thought to be life threatening.
John Hopkins, Chair of Rectory Park Residents' Association said the stretch of road has been a danger for a long time.
He added: "You only have to stand there and you see them speeding along, and it's supposed to be a 30 mile an hour speed limit."
Anyone with information should call Ealing Police on 0300 123 1212.