3.10pm UPDATE
The driver and sole occupant of a northbound vehicle involved in the crash has died at the scene.
A woman from a second, southbound vehicle has been taken to Whangarei Hospital with serious injuries.
Police say the highway will remain closed for up to three more hours.
Diversions are still in place.
1.35pm UPDATE
One person from each of the cars were trapped. Both have been freed and St John staff are treating the patients.
Diversions have been put in place through Hukerenui Rd and at the northern end of Jordan Valley Rd at Hikurangi to the south.
Police say motorists can expect delays for some time.
1pm: A crash involving two vehicles has meant police have shut State Highway 1.
The crash near Whakapara happened about 1pm. Police have shut the highway so that emergency services can get to the scene. Diversions will be put in place.
More soon.
Caring for her young partner to the end of his life inspired Williams to become a nurse.