Both children were correctly restrained in car seats.
Another crash in Tirohanga, between Pokuru and Tirohanga Rds, north of Taupo, killed Taupo woman Denise Tito.
Tito was grieving the loss of her mother and will share a double funeral with her.
The toll rose to three on Saturday morning after a motorbike and truck collided in Rotorua.
Horrified witnesses said the motorbike lost control and went under the truck's wheels.
The motorcyclist died at the scene despite members of the public trying to resuscitate the motorcyclist.
A police shooting caused traffic chaos on Sunday after a 27km section of State Highway 1 was closed between Woodcocks Rd and Silverdale for more than 12 hours.
A 29-year-old East Auckland man was fatally shot by police about 4am after coming towards officers with a machete.
He was shot dead near Pohuehue, north of Auckland.
The most recent crash happened about 9.15am on Sunday morning in Matamata.
Nine people were injured, two seriously, after multiple cars collided at the intersection of State Highway 29 and Hopkins Rd.
Traffic is expected to be heavy in places around the country tomorrow as people return from holiday and authorities are pleading motorists remain patient and alert.
NZTA has created maps to show the expected peak holiday traffic to help motorists decide the best time to travel to avoid queues.
The busiest areas and times are based on previous years' travel patterns.
Returning traffic will be heavy in those areas from late this morning to Tuesday evening.
Other North Island hotspots include Bay of Plenty, Coromandel and Waikato.
NZ Transport Agency safety and environment director Harry Wilson said more people on the roads meant it was important to plan.
"We don't want to see people getting impatient and taking unnecessary risks such as dangerous overtaking manoeuvres or following too closely."
Police said yesterdaythat motorists should consider leaving early in the morning or later in the evening to avoid peak travel times.
"Police want everyone to get home tomorrow safely after their Easter break, and ask that motorists take a moment to think carefully about their journey.
"Exercise patience in periods of heavy traffic. When you are on the roads, avoid distractions which can have dangerous consequences for yourself, your passengers and other road users," police said.
Police also recommend drivers are well rested to avoid fatigue.
"Each and every driver has a responsibility to themselves and everyone else on the road to ensure they make it to their destination safely."
Over Easter Weekend 2017 two fatal crashes killed two.
NZ Police assistant commissioner for road policing Sandra Venables said last Easter poor driver behaviour and speed were the main factors of crashes.
"We know the four main behaviours that contribute to road trauma are going too fast for the conditions, impairment such as fatigue, drugs or alcohol; distractions such as using a cellphone and not wearing seatbelts."
