Police are investigating the death of a one-year-old boy after he was struck by a vehicle in mid-west NSW.

Emergency services were called to a holiday park at Mumbil, about 75km southeast of Dubbo, about 11am on Saturday following reports a one-year-old child had been struck by a vehicle.

Officers arrived to find the toddler had been hit by a utility.

Ambulance paramedics treated the boy at the scene before he was airlifted to the Children’s Hospital at Westmead in a critical condition.

A crime scene was established and police have launched an investigation.

Police were notified about 5pm on Saturday that the boy had died in hospital.

Inquiries into the circumstances of his death continue.