It was too soon to release further details, they said.
Waipukurau chief fire officer Steve Walker said fire crews from Waipukurau, Waipawa and Omakere were called to the scene.
"We also called Hastings for a line rescue because the vehicle was 20m down a bank but we didn't actually utilise it."
One person managed to make it up to the roadside on his own and fire crews assisted with the retrieval of the deceased, he said.
A St John spokesperson said one person was treated at the scene for minor injuries and the rescue helicopter was dispatched but not needed.
The Christmas Eve fatality is the 22nd in Hawke's Bay, inclusive of the area between Wairoa and Tararua, this year.
It brings the region's road toll to the highest it's been since 2012, when there were 23 deaths.
Four people have now died on New Zealand roads this Christmas holiday road toll period, which began at 4pm on Friday and ends at 6am on January 3.
Taxi driver Abdul Raheem Fahad Syed, 29, was the first to die within the road toll period, and another person died in a crash in Northland about 5.45pm on Saturday.
The driver of a car died and a passenger was seriously injured in a crash at 12.40am in Hanmer Springs on Sunday.
The single-vehicle crash happened about 12.40am on Jollies Pass Rd when the car collided with a tree, police said.
The driver died at the scene and a passenger was transported to hospital by helicopter.
So far this year, 372 people have died on New Zealand roads, the highest number since 2010. The figure at this time last year was 311.
