A rear seat passenger in the Subaru died at the scene and the four other occupants were taken to Waikato Hospital by ambulance with serious injuries, police said.
Waikato Hospital communications director Mary Anne Gill said a 20-year-old woman and a 34-year-old woman were both in serious but stable conditions in the high dependency unit this morning.
But two boys, aged 5 and 12, were still in a critical condition.
The 12-year-old would be flown to Starship Hospital in Auckland today, and the youngest was set to be moved to the children's ward at Waikato Hospital.
State Highway 29 was closed with traffic diversions in place at both the Tauranga and Matamata side of the Kaimai Ranges.
The road was reopened at 9.20pm and police thanked road users for their patience.
Police Crash Analysts attended the scene and are investigating.
Police are appealing for any witnesses to the crash who have not yet spoken to police to contact Tauranga police on 07 577 4300.
EARLIER: A 9-year-old girl was killed and six people injured in a three-car crash in the Kaimai Ranges yesterday.
Three of the injured, including a 5-year-old boy, were in critical condition last night.
Sergeant Wayne Hunter of Tauranga road policing said four other people in the same car as the girl, understood to be members of the same family, were taken to Waikato Hospital.
A hospital spokeswoman said a 20-year-old woman, a 5-year-old boy and a 29-year-old woman were all in critical condition and under assessment by the hospital's specialised trauma team.
A 34-year-old woman was in serious but stable condition.
Two people were also taken to Tauranga Hospital -- a 55-year-old Mt Maunganui man, who was in a serious but stable condition, and a 79-year-old Tauranga woman, who was stable and comfortable.
Western Bay of Plenty area commander Inspector Clifford Paxton said the crash happened about 4.30pm on State Highway 29, near the Kaimai Ranges summit.
A westbound vehicle crossed the centre line and collided with an eastbound vehicle, Mr Paxton said. A third vehicle was also involved.
The crash comes on the eve of the Queen's Birthday holiday weekend, as police caution drivers to take care on the roads, in the hope of repeating last year's zero road toll.
Holidaymakers have been urged to drive to the conditions, with mixed weather forecast for much of the country.
Police assistant commissioner road policing Dave Cliff launched the "Make it to Monday" campaign yesterday, saying a reduced 4km/h speed tolerance would be in place from 4pm today until 6am on Tuesday.
"Drivers need to be mindful that holiday weekend driving is often more risky than other times, and adjust their driving accordingly."
Road safety charity Brake also advised caution.
"Every death on our roads is devastating for the family, friends and community involved. Remember them, and commit to driving slow and sober, and belting up, to help you reach your destination safely," director Caroline Perry said.
- Additional reporting Teuila Fuatai
