Police arrived at the crash scene at 5.40pm this evening near the Tarawera cafe.
The truck appears to have jack-knifed and crashed, blocking both lanes.
The driver of the truck suffered a medical event and is now in a serious condition in hospital.
The road will be closed for at least five hours, as there is a large diesel spill across the road which will need to be cleared.
Police are also waiting for a heavy haulage crane to right the truck and trailer before moving it off the road.
Motorists are asked to avoid the area until further notice.
/NZ Police Public Release. View in full here.
