Four people are believed to be injured following after a van rolled in Tasman.
Emergency crews were alerted to the crash near Murchison at around 2:30pm, and the road is closed near Pea Soup Rd and Maruia Saddle Rd.
A police spokesperson says eight people were in the van and some of those injured are in a critical condition.
Two helicopters have been sent to the scene.
Motorists are urged to avoid the Shenandoah Highway, and the serious crash unit is investigating.