State Highway 1 is closed in both directions south of Ward in Marlborough following a serious three-vehicle crash this afternoon.
Police said they were called to the scene about 2.50pm.
Initial indications were that one person had received critical injuries, and two others had minor or moderate injuries, police said.
NZ Transport Agency Waka Kotahi said the highway was closed from Ward to Wharenui.
It was expected to remain closed into this evening and no immediate detour was available.
Motorists were advised to delay travel through the area or NZTA said they could consider using the lengthy inland route via SH7, SH65, SH6 and SH63 as an alternative route.
Police said the Serious Crash Unit would carry out inquiries.
