"In particular, police want to hear from any truck drivers who were in the area between 5.45am and 6.20am. Police understand there were transmissions on the truck CB and RT radio comms indicating that drivers may have seen an object on the road around that time.
"Anyone with information should get in touch immediately by calling 105, quoting event number P043514278."
The road was currently closed and diversions were in place.
The police serious crash unit is at the scene.
Motorists in the area are being told to delay travel or to expect delays as authorities work at the scene.
The NZ Transport Agency earlier reported the incident to be a serious crash.