One man has died following a two-vehicle crash near Lumsden in Southland.
Emergency services were called to the scene about half past one.
A woman was reported to be in a critical condition.
Part of the Riverton-Wallacetown Highway is expected to remain closed for some time while the Serious Crash Unit investigates.
People are asked to expect delays or use alternative routes.
The death brings the road toll of this holiday season to five.