An investigation is underway following a serious crash involving five children in Matamata.

Police were alerted to the crash involving a Nissan Tiida on Morrinsville-Walton Road, Matamata at about 11.55pm.

Upon arrival police found the car in a ditch with five seriously injured children, aged 10 to 13, outside of the vehicle.

All five were taken to Waikato Hospital- four by ambulance and one by helicopter.

Four remain 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,” says Waikato District Commander Superintendent Bruce Bird.

'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.

'I also want to acknowledge the emergency service staff who responded,” says Superintendent Bird.

'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, is now open.

Image: Google Maps.