A boy believed to be just three has been critically injured after being struck by a car in west London, police said.
Officers have appealed for witnesses after the incident in Uxbridge Road, Hayes, on Sunday.
The driver of the car stopped and no arrests have been made.
In a tweet, Hillingdon Borough Police said: "We're working at the scene of a collision at 7pm between a car and a child in Uxbridge Road, Hayes.
"The boy, aged around 3 years, is critically injured. Driver of the car stopped; not arrested."
Anyone with information is asked to call police on 101.
Uxbridge Road was closed in both directions at the junction of Shakespeare Avenue, following the incident.
Photos from the scene show a heavy police presence.
A cordon had been placed at a set of traffic lights, as well as off a lamp post over the other side of the main road.
A dark blue Vauxhall car was parked behind police tape.
