Emergency services continue to work at the scene of the serious crash on State Highway 5, near Mamaku, about 20 minutes north of Rotorua, where a bus has rolled.
It is believed more than 20 people were on board the bus at the time of the crash.
A number of those passengers are reported to have been injured. Five helicopters and three ambulances have been reported to have gone to the scene.
The injured are being transported to hospitals in both Waikato and Rotorua.
Police have advised that there have been fatalities in the crash, however, the number cannot yet be confirmed.
The Serious Crash Unit and the Commercial Vehicle Safety Team are attending the scene alongside other Police staff.
The road is expected to remain closed for some time, and motorists are asked to avoid the area and delay travel.
More information will be released as it becomes available.