State Highway One has been reopened and traffic is flowing freely following three road crashes near Huntly on Saturday morning.
The first crash, which closed the main highway for a time, happened at 9.20am; two more followed on a diversion route that had been set up.
A van rolled on a bend and struck the front of a tourist bus carrying 34 people.
A man and a woman in the van were taken to Waikato hospital by helicopter with serious injuries.
Two children who were travelling with them have minor injuries and none of the bus passengers were injured.
A total of nine people received mostly moderate injuries in the three crashes.
At one stage traffic was backed up for about 14 kilometres.