Police believe the woman was crossing four lanes on St Albans Road near Elm Avenue and was waiting in the middle of the road to complete the crossing about 7am.
It is believed a dark coloured truck was travelling south when the woman stepped back to avoid it and was then struck by a white Mazda utility travelling north.
She was taken to hospital with head injuries.
Both the driver of the truck and utility stopped to assist the woman, however the truck driver left the scene prior to police arrival.
Police are keen to speak to the truck driver or anyone who may have witnessed the incident.
Anyone with information or dash-cam footage is urged to contact Crime Stoppers on 1800 333 000.