A truck and trailer unit carrying hazardous goods has rolled and crashed into a ditch on State Highway 49, near Ohakune.
Emergency services were called to the crash just after 3am today.
The driver received minor injuries and has been taken to hospital by ambulance.
The Fire Service is sending crews with Hazmat gear to assess the scene from Whanganui, about 70 kilometres away.
Police say people should expect delays, as heavy equipment is needed to right the vehicle.
One lane is closed, but emergency services are hoping to get a second lane opened soon.