Three people were injured, one critically, in a two-car collision late yesterday near Lyell, reducing State Highway 6 through the Upper Buller Gorge to one lane for most of the night.

The collision happened about 6km north-east of Inangahua Junction and close to the Iron Bridge across the Buller River.

The Nelson-Marlborough Rescue Helicopter answered the call-out, and a spokesman said one person was trapped and had to be cut from the wreckage by the fire brigade.

"Other occupants of both vehicles, despite their injuries, were able to free themselves with the assistance of passers-by," the spokesman said.

St John and the helicopter's on-board intensive care paramedic triaged and stabilised the injured; two were airlifted to Nelson Hospital with moderate arm, hand, chest and leg injuries, while a third was taken by ambulance to Buller Hospital, in Westport.

The Greymouth Star understands the latter, a 30-year-old woman, was later flown to Christchurch Hospital after her condition deteriorated. She was in a serious but stable condition today.

The highway reopened about 11 o'clock last night.

- Greymouth Star