Waka Kotahi NZTA said the road is closed between Te Kumi Station Rd and Mangarino Rd and will likely remain closed for some time as police carry out a serious crash investigation.
Hato Hone St John said two helicopters, three ambulances, a clinical manager, and a rapid response vehicle responded to the scene.
A St John spokesperson said two people were airlifted to Waikato Hospital and the other six were taken by ambulance.
A local was driving past the scene of the crash as emergency services arrived.
They said the van was heading south and crashed into a ditch but had managed to stay upright on its wheels.
“[Saw] a couple of guys lying down, one looked bad,” they said.
Another local said the crash happened by Lees Block Rd.
They believed the van was an old Toyota Hiace and that it had collided with a tree.