Five people were injured when a car flipped in the car park of a BP service station north of Wellington on Sunday afternoon.
Police say the car crashed into a bank and rolled at 12.23pm and there were five people in the car, at least one of them a child.
St John says it had five ambulances at the scene.
It says a helicopter was used to fly a man in his forties to Wellington Hospital with critical chest injuries.
Two other people were taken by ambulance to Wellington Hospital and another two were taken to Hutt Hospital.