Two men are dead and another is in hospital after a single vehicle crash near Ghost Lake, Alta.

Just after 4:30 a.m. MT, emergency crews responded to a call at Highway 40 and Range Road 73 near the Ghost Lake Campground after reports that a truck had rolled over an embankment.

EMS spokesperson Stuart Brideaux said it is believed the driver of the truck lost control and the vehicle fell more than 100 metres down to a riverbed.

Brideaux said the driver, a 19-year-old male, is believed to have climbed the embankment to call for help. He was flown to Foothills Hospital with serious injuries to his legs, frostbite and hypothermia. RCMP say he is in serious but stable condition.

RCMP say the three men were camping prior to the accident. (Meghan Grant/CBC) "It is rather extraordinary that someone was able to make it out of that environment," said Brideaux. "The overnight lows, just numerically at -23 are extreme enough as it is, factor in any windchill or any other exposure elements like being wet, being immersed in snow or having to move through snow while injured is quite extraordinary."

Emergency crews had to rappel down the embankment to evaluate the other two occupants, two males believed to be in their early 20s. Both were declared dead at the scene.

STARS air ambulance was called to provide lighting support and transport. Brideaux said the late hour and freezing temperatures made the rescue efforts difficult.

"Just the environment itself was actually very, very treacherous to be working in at that time of night and under those cold conditions," he said.

Driver attempted CPR on others

The three men appear to have been camping near Ghost Lake prior to the accident, about 600 metres from the cliff. Other campers in the area told CBC they were shocked by the group's lack of proper cold weather camping gear.

The deceased men had been riding in the open-air bed of the truck. Cst. Caleb Davisson said their bodies were found at the bottom of the hill — one close to the cliff and the other further out, both more than six metres from where the truck had come to rest.

EMS says the truck descended more than 100 metres to the frozen riverbed. (Meghan Grant/CBC) ​Davisson said the driver, who was wearing a seatbelt, knew he was approaching the lookout but his truck failed to stop. The driver told RCMP he tried to do CPR on his friends before climbing the cliff to get help.

"If he hadn't been wearing a seatbelt, he wouldn't have survived," he said. "And then the fact that he must have been in incredible pain but he still checked on his friends and made it back is quite an impressive feat."

The three men are said to be childhood friends.

RCMP are investigating the cause of the crash.