Investigations will continue today after a woman was seriously injured on Great Barrier Island after being hit by a car.

Westpac Rescue Helicopter Trust said it was called to the case at 7.51pm.

"The Friday evening crew of the Westpac Rescue Helicopter (Westpac 2) were tasked to Tryphena, Great Barrier Island to assist a female patient in her 50's who had exited a ute leaving the handbrake off," said Trust spokesman Lincoln Davies.

"The vehicle rolled backwards, rolling over her and crushing her."

Davides said the woman suffered multiple injuries and was flown to Auckland City Hospital in a critical condition.

Police and ambulance were called to the crash on Puriri Bay Rd at 7.45pm on Friday.

The woman remains in critical condition in Auckland Hospital.

Police investigations are ongoing.