Horror 10 hours on roads: Four dead in crashes in Whanganui, Buller, Matakana and Canterbury

The toll that road deaths takes on first responders.

Four people have died in separate crashes over 10 hours across the country.

The crashes between about 4pm on Saturday and 2am this morning happened in Whanganui, Buller, Matakana and Governors Bay in Canterbury.

One person died in a two-car collision on Cross St in Castlecliff, Whanganui, early on Sunday.

Police were alerted to the crash just after 2am, and a spokeswoman said inquiries into the cause of the crash were ongoing.

One person was also killed in a single-car crash at Maimai Valley, in the Buller District, about 8.35pm on Saturday.

Police received a report that a car had gone off the road. A person was declared dead at the scene.

A second person in the car sustained minor injuries.

Another person died after a serious crash at Matakana Rd, north of Warkworth, about 6pm on Saturday, police said.

The single-vehicle crash occurred between Oak River Dr and Wright Rd, southwest of the Matakana village.

"Sadly, the occupant of the vehicle has since died of their injuries," police said in a statement.

An investigation by the Serious Crash Unit into the circumstances of the crash is ongoing.

And a fourth person died following another serious crash on Teddington Rd in Governors Bay, Canterbury, at 3.55pm on Saturday.

The crash involved a car and a motorcycle and happened between Allandale Lane and Church Lane.

"Sadly, the motorcyclist died at the scene," police said.

The driver of the car was also seriously injured.

Police said a scene examination was carried out by the Serious Crash Unit and an investigation was under way.