Dunn said one injured person was able to clamber up the bank with help from firefighters but the other had to be hauled up in a basket using a rope pulley system.
Both were treated by ambulance officers for leg injuries before being flown to Christchurch Hospital with the driver and front seat passenger who managed to get out on their own.
An ambulance spokeswoman said all escaped the crash with minor injuries.
Dunn said the pine trees averted catastrophe.
"If the pines were not there the car would have dropped to the bottom."
He said overnight ice had left the steep and windy gorge road in a treacherous state.
"Firefighters told me it was very, very difficult to stand up on the road let alone drive on it," he said.
Grit had been spread over 2.5km near where the crash happened to improve traction.
A police spokeswoman said ice was creating hazardous conditions across the region's roads today.
Meanwhile, a person is seriously injured after a serious smash near a South Auckland high school this morning.
Police say a ute and truck collided near Wesley College on State Highway 22 about 8.45am.
A spokeswoman said one person was trapped in the wreckage and needed to be cut free by firefighters.
The motorist suffered serious injuries, she said.
