The sole occupant of the Mazda, a Kaitaia woman, was not trapped but a Kerikeri fire crew cut the side off her car so she could be removed without risking further injury.
Both drivers were flown to Whangarei Hospital in a serious condition by the Northland Electricity Rescue Helicopter. The driver of the Toyota had severe lower limb injuries.
Sergeant Tony Dunckley, of Kerikeri police, said initial indications were that the driver of the Mazda had veered across the centreline. There was no suggestion that overtaking or dangerous driving was involved. Neither weather nor the road was thought to be a factor.
Police would release the victim's name once her identity had been confirmed and her next of kin informed.
The police Serious Crash Unit was investigating, Mr Dunckley said.
The highway was expected to remain closed until at least 6.30pm but with traffic diverted via Taumatamakuku Settlement Rd there were no major delays.
Kawakawa Fire Brigade station officer Alistair Leitch said the volunteers had been called to a number of crashes in recent days, some of which had occurred on roads made greasy by rain after a long dry spell.
There was no indication that was a factor in the latest crash but he urged Northlanders to take extra care on the roads in the lead-up to Christmas.
The scene was blessed by kaumatua Wiremu Wiremu.
The crash brought Northland's road toll this year to 15. There were 21 road deaths in Northland in 2013.
