A primary school camp ended badly when three children and a parent were transported to Waikato Hospital today.
The car they were in collided with another vehicle outside Pokuru School, near Te Awamutu.
A number of vehicles were returning children to the school after a week-long camp near Lake Taupo.
The driver of the second car was uninjured.
An air ambulance transported one young girl to hospital. She is described as being in a serious condition.
Pokuru Road was closed to allow Serious Crash Investigators to conduct a scene examination and determine the cause of the collision.
Victim Support attended at the scene to provide support to parents, pupils and teachers of the school.
The Pokuru School website says the children are from farming families in the Pokuru, Te Kawa and Te Mawhai areas and a number of children live in Te Awamutu and commute to the school daily.