His friend's wrist ''was like a horror movie - his bone was popping through his skin'', Mr Weale said.
Mr Salter quickly complained he could not feel much below the neck.
Ambulance paramedics, who have been commended by a hospital doctor for protecting Mr Salter's spine, took him to Lakes District Hospital.
A specialist team then arrived from Christchurch by helicopter to collect him.
There is hope Mr Salter will recover, but doctors at Burwood spinal unit are unsure whether he will walk again.
Mr Salter's mother has arrived from the United Kingdom and his father is expected to fly in today.
St John Wakatipu station manager Craig Downing, an ambulance officer for 27 years, said Mr Salter was ''a remarkable young man''.
It was a tragic event for everyone concerned, Mr Downing said.
''It's one of those jobs that even in an ambulance career you don't come across very often.
''I think, generally speaking, it affects everyone who's involved in it - because we're all reminded that, in an instant, life can change, in the most spectacular way.
''One minute you're living life in the absolute extreme on the other side of the world, the next minute suddenly everything's different.''
Employer Tradestaff said Mr Salter had worked for the company since April. He had recently finished working on The Remarkables skifield's new base building and was due to start a new job.
Senior consultant Claire Pickup said he did a great job for many clients and had travel plans.
True Line Builders director Jaden Melgren, of Arrowtown, said shocked workmates at The Remarkables building site had raised money for Mr Salter.
''I was hoping that with him being a backpacker that maybe the backpacker community of Queenstown would reach into their pockets and give him a hand.''
Nick Hamlin, of Arrow International, the base building job's project manager, said Mr Salter had worked on several of Arrow's projects and was a ''really good worker''.
''It's pretty tragic, really.''
