Police said both children were correctly restrained in their car seats.
The serious crash unit and the commercial vehicle safety team are investigating the crash, in the southbound lane of State Highway 1 north of Waiouru, between Waipakihi Rd and Rangipo Intake Rd.
The road between Waiouru and Rangipo was closed on Friday, forcing traffic to detour via National Park. It reopened late Friday evening.
So far four people have now died on the roads over the long Easter weekend. That makes the Easter weekend road toll already double that of last year and police are urging motorists to exercise caution when driving.
The official Easter holiday period for 2018 began at 4pm Thursday, March 29, and will end at 6am on Monday.
A crash in Tirohanga, between Pokuru and Tirohanga Rds, north of Taupo, killed Taupo woman Denise Tito. She was grieving the loss of her mother and will share a double funeral with her.
And a person died in a crash in Rotorua involving a truck and a motorcyle.