RNZ reported the two people had been stabbed.
The vehicle then left the road and crashed, police said.
Emergency services carried out CPR on one of the victims but they died at the scene.
The second victim was taken to hospital with moderate injuries.
Road closure near Matatā after a serious incident. Photo / Google Maps
The alleged offender was arrested at the scene.
“A scene examination is now under way and the road is expected to remain closed for some time,” police said last night.
“Diversions are in place, and motorists are asked to avoid the area.”
Hato Hone St John said they took one patient to Whakatāne Hospital in a moderate condition and referred further inquiries to police.
Raphael Franks is an Auckland-based reporter who covers business, breaking news and local stories from Tāmaki Makaurau. He joined the Herald as a Te Rito cadet in 2022.
Sign up to The Daily H, a free newsletter curated by our editors and delivered straight to your inbox every weekday.