Mr Row said police believed the Subaru Justy also collided with a second car heading north and that vehicle also had a couple on board.
Two men and two women from the northbound vehicles suffered moderate injuries.
The female driver of the car heading south died at the scene.
Cars and light vehicles were detoured on to Akerama Rd then Ruapekapeka Rd, while heavy traffic waited on the side of the road between Akerama Rd and Paiaka Rd.
Traffic was also diverted through Towai Rd, Callaghan Rd and Maromaku Rd.
A kaumatua blessed the scene before the woman's body was removed.
The Serious Crash Unit surveyed the scene.
Mr Row said SH1 was expected to be fully opened to all traffic by 6.30pm tonight. Associate Minister for Transport, Shane Jones said he was horrified to hear of the second fatal car crash on Northland roads in three days.
"It's an awful tragedy and my aroha goes out to all the whanau."
He said whatever the cause of the accidents, questions about the condition of Northland roads would likely arise.
"We need to improve the level of investment and the access to funding to enable the North to improve the most egregious conditions of our roads," Mr Jones said.
