A young boy was rushed to hospital after he was hit by a motorcycle in a horror crash on a busy road in west London.
Police and paramedics raced to the scene in South Ealing shortly after 12.15pm on Saturday.
A boy, aged around nine or 10 years old, suffered serious head and leg injuries in the crash and was taken to a central London hospital where he remains, police said.
Officers are urgently trying to locate the parents or carers of the boy as it appears he was alone at the time of the incident, which happened in Popes Lane, at the junction with Knight’s Avenue.
At this early stage it is believed that the boy got off a Route E3 bus and moments later the collision occurred.
The child is described as a white boy, 4ft to 4ft 5ins tall and has dark coloured hair.
He was wearing a black 'Parka' style anorak, with a fur edged hood and red lining. On the anorak there is a leather disc with a logo and the words 'Get outdoors'.
The boy was also wearing beige trousers and black 'tie dye' Nike trainers, with the Nike tick in fluorescent green.
The motorcyclist stopped at the scene. They were not arrested and are assisting detectives with their enquiries.
Anyone who can assist with indentifying the boy or who witnessed the collision is asked to contact the Serious Collision Investigation Unit at Alperton Traffic Garage on 020 8991 9555, 101 or via Twitter @MetCC