A plane that crashed Sunday near the peak of Atigun Pass was carrying three tourists from New Brunswick, Canada, who were participating in a flight-seeing tour, according to the North Slope Borough.

Forest Kirst, 57 of Fairbanks, was piloting a Navion L-17A registered to his company, Kirst Aviation. On board were Darrell Spencer, 66, Daphne McCann, 65, and Marcene Nason, 65.

The passengers were visiting Alaska on a tour operated by  Princess Cruises.

What went wrong remains unclear, but the mountain where the plane ended up is about 5,000 feet high and amid a commonly-flown route that connects Fairbanks to many North Slope communities, according to National Transportation Safety Board spokesperson Clint Johnson.

Johnson said that earlier in the day, the plane departed from Fairbanks International Airport with a planned day-trip to Bettles, Deadhorse and Barter Island.

They never made it beyond Bettles.

Johnson said Alyeska Pipeline security personnel spotted the crashed plane about 400 feet from the summit around 1:45 p.m.

"There was no post-crash fire, thank heavens," Johnson said.

That and a quick response is why the plane's occupants were able to be quickly transferred for medical treatment: "Up here, there's no jurisdictional thing, it's whoever can get there the fastest," said D.J. Fauske, North Slope Borough spokesperson. "They made it out thanks to the good folks over at Alyeska Pipeline."

Fauske said an Alyeska helicopter lifted them out, and he said the passengers are now en route to Vancouver.

Their medical condition is not immediately known, and while the tour was not Princess-operated, company spokesperson Bruce Bustamante said the company's care team is providing support to the guests and their families.

"Our thoughts and prayers are with them for a full recovery," Bustamante said.

Providence Alaska Medical Center spokesperson Ginger Houghton said Monday afternoon that Kirst is listed in fair condition.

Federal investigators plan to interview Kirst when his condition improves to learn about the moments leading to the crash, Johnson said.

Editor's Note: A previous version of this story incorrectly included a reference to "employees," while the passengers of the airplane were in fact customers. The story has been corrected.