Police are requesting patience from motorists while they deal with a serious crash on State Highway One, in north Otago.
A truck and trailer unit and a tractor are involved, about three and a half kilometres north of Hampden.
The road has been closed but because of the location of the crash and there is no detour available.
The road's expected to be closed for about two hours and police are warning motorists there will be a long backlog of vehicles in both directions.