Boy, 6, hit by car on Sydney crossing

A six-year-old boy remains in serious condition in hospital after he was hit by a car as he crossed the road in Sydney's west.

The boy was treated for serious head and facial injuries at Regents Park about 8pm before being taken to The Children's Hospital at Westmead where he remains in a serious condition.

The male driver of the vehicle was taken to Auburn Hospital for testing and police are calling for witnesses as they continue their inquiries.