An eight-year-old child was critically ill and a six-year-old seriously injured after a collision between a logging truck and school bus near Ruatoki in the eastern Bay of Plenty on Monday.
In all, 36 people needed medical treatment and were taken to Rotorua, Tauranga and Whakatane Hospitals.
The two most seriously injured children were in Rotorua Hospital.
The truck driver was in a stable condition in Tauranga hospital and the school bus driver was not injured.
The Eastern Bay of Plenty Area Commander, Inspector Sandra Venables, says it appears the un-laden logging truck ran into the back of the school bus but police are investigating exactly what happened.
The impact sent both vehicles into a nearby paddock, and caused the truck trailer to roll.
The bus was carrying students from Trident and Whakatane High Schools, and primary school students from Taneatua.
Police say, due to the number of different schools involved, they are still confirming how many students were on the bus.
Inspector Venables says many locals in a tight-knit community were on the scene quickly and their efforts in helping emergency services were remarkable.
She says families wanting more information are asked to contact the Whakatane Police Station on 07 3085255.
Witnesses describe the scene
A Youthtown Rescue Trust Helicopter pilot, Nat Every, transported one of the young children with serious injuries to Rotorua Hospital.
He says he was in flight when he received the emergency call - and it took about half an hour to get to the scene.
Mr Every says it was the biggest crash scene he has ever attended.
A community newspaper photographer who attended the scene said the rear of the bus was severely damaged.
Troy Baker of the Whakatane Beacon told Checkpoint the back of the bus had been pushed in about a metre by the impact.
He said, however, that the bus was a rear engine vehicle and the motor appeared to have absorbed the bulk of the impact.