In a Facebook post detailing the accident, school board member Mark Eades said the injured pupil had been taken to hospital and "our thoughts are with the family".
The school remained open, with the focus now on supporting pupils and staff.
Neighbouring schools had been notified about the accident, he said.
Access to the school via Wells Rd was currently blocked while police investigated the accident.
"We will endeavour to keep our community updated whilst respecting the wishes and privacy of the family involved.
"Thank you to everyone for your ongoing support," said Eades.
The Ministry of Education's specialist team who would be providing support to the students, staff and community.
Two ambulances and two rapid response units were called to the crash scene around 8.40am.
St John treated one patient who was in a critical condition.
Fire and Emergency NZ confirmed they were at the scene of an accident involving a car and pedestrian.
A police spokesman said at 8.40am, police were notified of the crash involving a vehicle and pedestrian.
The pedestrian, a child, was in critical condition and being transported to hospital.
The Serious Crash Unit has been notified and will be examining the scene. He said the board had contacted the Ministry of Education's specialist team who would be providing support to the students, staff and community.