Senior Sergeant Glenn Saunders of Tauranga police said at the scene that the seriously injured woman had been thrown from the car during the crash.
The 36-year-old was in a critical condition when she was airlifted to Waikato Hospital by the Rotorua-based BayTrust rescue helicopter about 4.30pm.
It was understood a member of the public took some occupants of the car to hospital before emergency services arrived, leading to initial confusion over how many people had been in the car when it crashed.