A section of State Highway 60 near Nelson was closed after a fatal crash on Friday morning.
The crash, involving a truck and car west of Nelson, was reported to police just before 9.30am.
Police confirmed this afternoon that one person had died following the crash.
"Enquiries are ongoing into the circumstances," a police spokesperson said.
St John treated two other people at the scene of the accident.
Firefighters were also called to extinguish a blaze that started as a result of the crash.
The highway between Gardner Valley Rd and Aporo Rd was still closed on Friday afternoon and diversions were in place between the two intersections.
It is expected to be closed for some time and the detours are suitable for heavy vehicles.
