A 66-year-old Blenheim woman was trapped in her car for more than an hour yesterday after a freight truck and two cars collided on State Highway 1, near Rai Valley.
Emergency services said it was "absolutely miraculous" that no-one was killed or seriously injured in the accident at Collins Valley.
Rai Valley chief fire officer Trevor Holdstock was one of the first on the scene.
He said a passerby drove to the Rai Valley fire station to report the accident after he came across it about 11.30am. There was no cell phone reception at the crash site.
"The guy said ‘it's bad'," Mr Holdstock said.
"You're gonna see dead bodies."
Mr Holdstock said when he got to the scene and saw a 13-metre container truck had smashed into one car and landed on top of another, he expected the worst.
"I honestly thought, ‘oh dear, we've got a K41 [fatality], or two or three'," he said.
Mr Holdstock was shocked when two Argentinian men who had been sitting near the road barrier told him in broken English that they had escaped from the crushed car.
"If you came face to face with what we saw, it was shocking," he said.
"How people walked out of that without dying is unbelievable."
He said it took about an hour for firefighters to free the Blenheim woman.
"She was pretty pinned down," Mr Holdstock said.
"She'd been crunched up in a horrible angle for a while."
The woman was flown by Nelson Marlborough rescue helicopter to Wairau Hospital, in Blenheim, with moderate injuries to her lower back and face, along with her passenger, a 70-year-old male.
A hospital spokeswoman said yesterday evening the woman was in a stable condition.
The man had been treated and discharged, the spokeswoman said.
St John Ambulance shift manager Mike Casey said the eastbound TNL freight truck, which was carrying empty wine bottles to Blenheim, appeared to cross the centreline before tipping and colliding with two cars travelling in the opposite direction.
"Given the initial assessment of the damage it is absolutely miraculous that no-one was injured in the second car," Mr Casey said.
"Sometimes you just wonder how on earth do people just walk away in these types of incidents."
The accident closed the state highway, and although one lane was briefly reopened, it was closed again later in the afternoon so the truck could be righted and towed.
The highway re-opened about 4.30pm.
Mr Holdstock estimated traffic was backed up about three kilometres on the Blenheim side of the closure between Rai Valley and the bottom of the Whangamoa Saddle.
Senior Constable Beau Webster, of Havelock, said he believed speed had been a factor.
The driver of the truck, who was extremely shaken, appeared to have been going too quick around the corner, he said.
Mr Webster said TNL took the Argentinian men to Nelson and put them up in a motel.
The men were extremely lucky to be alive, he said. One received only a minor injury when he cut his hand getting out of the car.
He said he had also spoken to the driver of a third car, which managed to narrowly avoid the crash.
The man and his woman passenger, a nurse, were in front of the two cars heading toward Nelson when they saw the container on the truck start to tilt.
The driver put his foot down and saw the truck collide with the first car and land on the other car when he looked in his rear-view mirror.
A police spokeswoman said an investigation was under way.
Rescuers said the two Argentinian men returned to their crushed vehicle to retrieve possessions from the wreckage as it remained pinned under the truck.
They could even muster a laugh when asked if it was the latest type of convertible.
The Marlborough Express