Police said the Holden Commodore the five men were in was overtaking in a dip in the road, just north of the Makatote Viaduct, when a truck and trailer came around a corner from the opposite direction.
Inspector Steve Mastrovich told APNZ the car "smacked head-on into the truck and trailer''.
A tow truck driver who attended the scene of the crash said the lorry went right over the car, crushing it to the back seat.
All of the men were seasonal staff at Whakapapa skifield, and police were working with Argentine consular staff to advise the men's families.
Ruapehu Alpine Lifts general manager Dave Mazey said four of the men had worked in the cafeteria at Whakapapa, and one was working in the rental operation. One of them had worked at the skifield last season.
The men were part of a large, close-knit group of South American staff who worked at both the Whakapapa and Turoa skifields.
"They were all outgoing people. They all have a strong zest for life,'' Mr Mazey told APNZ.
"Staff work, live, play together in relatively close circumstances ... They tend to get relatively close in a short a space of time - they all have a strong common interest in skiing or boarding.''
Mr Mazey said a lot of staff were very upset this morning.
"A number of close Argentinian and Chilean peers that were rostered on today didn't stay. Some of them I understand went through to Hamilton to be be with their friend who's critically injured.''
The company was providing on-site support to affected staff.
Mr Mazey said a number of Argentine and Chilean staff had been travelling around the country in the months before the ski season.
They would have been reasonably familiar with driving conditions in New Zealand, he said.
Police were to examine the car and the scene, as well as toxicology results, to establish the factors that contributed to the crash.
Mr Mastrovich said there were no-passing lines on some sections of the road.
"In daylight you would see that straight and you would think it's not quite long enough to pass.''
Any prudent driver would not have overtaken another vehicle along that section of road, he said.
He said the tourists were driving in different circumstances to what they would have been used to.
The tow truck driver who attended the crash last night, Colin Fredricksen, told APNZ it was one of the worst crashes he had seen on the job. "I've seen others that have been bad, but not so many people involved.''
He said the truck had crushed the car.
"He ran straight up over the top of the car, it smashed the motor and suspension completely out of the car, and squashed right to the back of the back seat,'' Mr Fredricksen said.
"These guys had no show of survival, there was no way they were going to survive with the truck running dead over the top of them.''
Mr Fredricksen said he spoke to the truck driver this morning, who could only recall seeing the headlights of the oncoming car before the crash.
Bryan Finnerty, from the Crossing Backpackers Ski Lodge in National Park, said the weather conditions last night were better than it has been all week.
There had not been a frost in the area for the past two days, and there was no ice on the road.
"The weather was good, and the road conditions were excellent,'' he said.
"It's a bit of a worry because it's the second large fatal accident in the last four months [in the area].''
Two months ago, three American exchange students were killed when the van they were travelling in rolled near Turangi as they made their way to the Tongariro Crossing.
