Occupants of two cars have been seriously injured in crash in the Waikato overnight.
Emergency services were called to State Highway 1 in Tamahere just before 5am.
The Police Serious Crash Unit is investigating the cause
Diversions are in place between State Highway 1 and Newells Rd, Hillcrest, and State Highway 1 and Airport Rd, Tamahere.
Motorists are advised avoid the area and to take alternate routes.