A subsequent police statement said initial reports were that three vehicles were involved and two helicopters were being sent to the scene.
A Fire Service spokesman said five fire appliances attended, including two carrying the jaws of life, and assisting cutting the victims out of the wrecked vehicles.
Barbara Bowen, who owns the nearby cafe Xpresso Souvlaki Pareora about 100m from the crash scene, said she heard a "huge bang".
"It was really bad crash and they're still working on it," she said when speaking to the Herald about 5.30pm.
"It looks like it was a head-on collision and basically all the cars are right off the road - they're nowhere near the road, they're just off the road. It must have been a pretty bad hit."
Helicopters were coming and going ferrying the injured to hospital.
The road is blocked and diversions are in place.
6.00AM 3 SEP UPDATE: Road is now OPEN
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8PM UPDATE
The road remains CLOSED. Check our website for further details:...