One person has since died, a police spokesperson said.
Both fatal crashes are now under investigation.
On Sunday morning, police investigating a car fire in Flat Bush, south Auckland, also confirmed a person had died.
Emergency services were called to the fire on Chapel Road at about 8:10pm on Saturday. A body was subsequently located inside the vehicle.
Another person was seriously injured on Saturday night after a car rolled on Matakana Road in Warkworth, north Auckland.
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