A person is critically injured after a crash on State Highway 4 near Whanganui.
The crash happened at Upokongaro, about 10km north of Whanganui, shortly before 2pm on Sunday, police say.
The north-bound lane of SH4 is closed and the south-bound lane has stop/go control in place.
The Serious Crash Unit is investigating.
Motorists are asked to avoid any unnecessary travel in the area.