Police said more than 20 people were in the vehicle when it crashed and rolled on a highway about 20 kilometres (12.5 miles) west of Rotorua -- a popular tourist town known for its hot springs.
"Police can advise there have been fatalities in the crash, however the number cannot yet be confirmed," they said.
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Media reports said the passengers included tourists from China and that a Mandarin translator had arrived at the crash scene to help survivors.
Local newspaper reported six people were feared dead.
St John Ambulance service said five helicopters and five ambulances had been dispatched and patients were being transported to hospitals around the region.
It said two people had serious injuries, four moderate and a further 15 were undergoing assessment.
Attempts to contact the Chinese embassy in Wellington were unsuccessful.
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