State Highway 73, near Arthurs Pass in now open with one lane after a crash closed the highway earlier this afternoon.
Five people were injured, but their injuries were "not believed to be life-threatening", said Christchurch police shift inspector John Doherty.
All the injured had been taken from the scene by rescue helicopter by the time police arrived.
He could not confirm the number of vehicles involved.
Police would try to reopen the remaining lane soon.
