Five young children were seriously injured after they were flung from their vehicle in a crash near Matamata.
Arriving at the scene about 11.55pm yesterday, police found the Nissan Tiida in a ditch on Morrinsville-Walton Rd with the five children - aged 10 to 13 - outside the car.
All five were taken to Waikato Hospital - four by ambulance and one by rescue helicopter.
Waikato District Commander Superintendent Bruce Bird said four today remained in the Intensive Care Unit in a critical condition and another is in a ward in a stable condition.
"At this early stage our focus is on understanding what led to this very serious crash.
"While we understand there may be speculation about what occurred, it's important police have the opportunity to investigate the circumstances, and the families impacted are given the space to support their children."
Police would like to thank the members of the public who went to the children's aid immediately after the crash.
Bird acknowledged attending emergency crews.
"They acted quickly and professionally in difficult conditions to ensure these young people got the medical attention they urgently needed."
The crash site, while initially closed to traffic, had since reopened.
The MP for Rangitīkei was seen texting while at the wheel of her branded vehicle.