A truck and trailer has rolled down a bank in Waikato, trapping the driver.
He has been taken to hospital with potentially life threatening injuries.
The accident happened shortly after 2.30pm this afternoon, as the heavy truck and trailer was travelling north-bound on State Highway 1, near Lake Karapiro, in the Waikato.
The truck drove off the road, ending up down a large bank, approximately 1km south of Becks Nursey.
One of the two north-bound lanes was closed to traffic, Inspector Steve Kose said.
He said the lane closure would be in place for sometime and further lane closures were likely as the truck was pulled back to the road.
Police advise motorists to avoid the area and to take alternative routes if possible.