Two children are in a critical condition after two cars collided head-on in Sydney's west on Tuesday afternoon.
Nine people, including three children, were injured in the crash on Mamre Road, near Abbotts Road in Kemps Creek about 1.30pm.
Three children have been taken to Westmead Children's Hospital, two in a critical condition.
Five adult patients have been taken to Westmead Hospital; one has also been taken to Liverpool Hospital in a critical condition.
A major operation is underway to treat the injured, with 14 paramedic crews including two rescue helicopters on the scene, as well as three NSW Ambulance chaplains.
Traffic is being diverted along Bakers Lane, Aldington Road and Abbotts Road.