A Dunedin man and his son were involved in a fatal head-on crash that killed two people, including the father, near Haast on Wednesday.
The drivers of both vehicles are still in hospital being treated for their injuries, after one of the vehicles crossed the centre line.
A New Zealand man, aged in his 40s, who was driving a Subaru, underwent surgery at Dunedin Hospital on Wednesday, police said.
His condition was not considered life threatening.
The man's 82-year-old father, from Dunedin, who was a front-seat passenger in the car, died in the collision.
A German man, who was driving a campervan, is in Grey Base Hospital. He has lacerations to his legs, a broken collarbone and a heart condition.
A 53-year-old woman passenger in the campervan, also from Germany, died on the way to hospital after the crash.
The serious crash investigation was almost complete and both lanes on the road were open.
The names of the deceased could not be released yesterday, as all relatives had not been contacted.
West Coast police urged motorists to take extreme care on the roads, to keep left and drive to the conditions.
Constable Nerida Manson, of Haast, said the 4pm crash was caused by one of the vehicles crossing the centre line.
The collision took place on a "significant, but not sharp, bend".
Constable Bill Parker, of Franz Josef, said the campervan bore the brunt of the collision.
"The campervan was all crumpled up. The front was pushed right back to the seats."
The Tasman police district serious crash unit investigator and Greymouth CIB detectives were on site yesterday and were seeking the driver of a white bus that may have been first on the scene of the accident.
They have asked the bus driver to contact them, because he may have information pertinent to the investigation.
Const Parker said the South Westland highway was busy over the holiday season and with so many foreign drivers on the road, he urged all motorists to exercise patience and restraint.
"You can't be too careful."
The South Westland fatalities, followed by the death of a 21-year-old Christchurch man whose car crashed into a power pole in Woolston at 2am yesterday, took the Christmas-New Year road toll to 11.
• A Dunedin woman received minor head injuries after the car she was driving was in collision with a van in Kaitangata yesterday.
The crash happened at 5.05pm. The woman and a passenger were in a Suzuki Alto, which collided with a Ford Falcon carrying three people, at the intersection of Exmouth and Eddystone Sts.
Constable Andrew Denny, of Balclutha, said driver inattention appeared to be to blame, but no decision on charges had yet been made.
