A plane that went missing in Antarctica slammed into a mountain and there are not believed to be any survivors, rescuers said Saturday.

Three Canadians were on board the Twin Otter aircraft when it went missing Wednesday about halfway between the South Pole and the McMurdo Station research center.

“The aircraft wreckage is on a very steep slope, close to the summit of Mt Elizabeth. It appears to have made a direct impact that was not survivable.  No details are available on the cause of the crash,” Maritime New Zealand, which has been coordinating the search operation, said in a statement. “The next of kin have been informed.”

It said the site of the crash was at the northern end of the Queen Alexandra mountain range at an altitude of about 13,000 feet.

Two helicopters reached the site at around 7.15 p.m. New Zealand time (1.15 a.m. ET), but were not able to land.

Rescuer Tracy Brickles said in the statement that it was very sad end to the operation.

“It has been difficult operation in challenging conditions but we remained hopeful of a positive result. Our thoughts are now with the families of the crewmen,” she said.

The Calgary Sun newspaper previously identified one of those aboard the plane as Bob Heath of the Northwest Territories, calling him a “star pilot” for Canadian firm Kenn Borek Air, which owns the plane.

In an emailed statement, Kenn Borek Air said one of its aircraft and a New York Air National Guard plane had also made “visual contact” with the crash site.

“No signs of activity are evident in the area surrounding the site, and it appears that the impact was not survivable,” the statement said.

It added that helicopter crews and mountain rescue teams would attempt to get to the site.

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