A 72-year-old man is in hospital with life-threatening injuries after being hit by a bus.
Police were called to the collision at Printing House Lane in Hayes, west London, at around 3:45pm on Saturday.
The bus involved was on the E6 route between Rockware Avenue and Bulls Bridge Tesco in Houslow, and the driver stopped to assist officers with their enquiries.
The pedestrian was airlifted to an east London hospital and his next of kin have been informed. No bus passengers were hurt.
No arrests have been made but Road and Transport Police officers are "speaking to a number of people" and are appealing for witnesses and passengers to get in contact.
Witnesses are urged to call 020 8991 9555.