A woman is in critical condition following a crash on State Highway 6 north of Nelson.

Three others sustained moderate injuries after two vehicles collided near the Glenduan turn-off at Wakapuaka this afternoon, Stuff.co.nz reported.

One News reported some passengers had been trapped inside their vehicle.

Police say the road will be closed until further notice due to the serious nature of the incident and are advising motorists to alter their travel plans to avoid delays.