Two women and two children have been flown to hospital in Perth with serious injuries after a traffic crash in Port Hedland.

Authorities say a car crashed into a light pole in Cook Point yesterday afternoon.

A spokeswoman for the Royal Flying Doctor Service says the children, aged six and seven, suffered serious head injuries, broken legs and possible spinal injuries.

The two women, aged 24 and 34, suffered broken legs and one of them a fractured pelvis.

Three RFDS planes transported the women to Royal Perth Hospital and the children to Princess Margaret Hospital late last night.

It is believed they were not wearing seatbelts when the crash happened.