One person has died following a collision between two trucks on SH65, 9.5kms north of Springs Junction.
Another person has been taken to Greymouth Hospital by helicopter.
Police were alerted to the crash just before 10am.
Diversions are in place.
Northbound traffic should use SH7 to Reefton.
The detour route for southbound traffic is SH6 from Murchison then SH69 to Reefton and onto SH7 to Springs Junction.
All motorists are advised to avoid the area if possible and to drive with care.