The two adults in the van were on their way home to Auckland.
A child and a grandmother in the Subaru suffered serious injuries and were flown to Whangārei Hospital by the Northland Rescue Helicopter, which landed on the sports field at nearby Oruaiti School.
At least one patient in the Subaru had to be cut out of the wreckage by volunteers of the Mangonui Fire Brigade.
The northbound lane of SH10 was blocked with traffic allowed through one direction at a time. The highway was fully re-opened about 10.30am.
Meanwhile, emergency services are responding to a non-injury crash involving a school bus and a tractor, 32km south-west of Whangārei.
Sergeant Ryan Gray said a tractor travelling on Walker Rd, Waiotira, had rolled. A school bus driver had to take evasive action to miss the tractor about 9.16am.
A tractor rolled onto it's side as a school bus was travelling in the opposite direction on a narrow rural road southwest of Whangarei. Photo / John Stone
Gray said no one was injured and all the students had been taken off the bus.
SH10 MANGONUI - CRASH - 9:10AM Following an earlier crash, Stop/Go traffic management is in place at the intersection of SH10 and Taupo Bay Rd, east of Mangonui. Please expect delays in the area and drive with extra care. ^TH
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) November 4, 2018
