Three people are injured after a two-vehicle crash on State Highway 8, south of Twizel.
A police spokeswoman said emergency services were called to the crash, near the intersection with Mcaughtries Road at 12.53pm.
One patient suffered serious injuries, one moderate and one minor, a Hato Hone St John spokeswoman said.
A helicopter had been dispatched to transport the seriously injured patient to Christchurch Hospital.
NZTA Waka Kotahi said delays were possible.