Petr Kellner, the Czech Republic’s richest man, has been killed in a helicopter crash in Alaska.
The billionaire’s death, along with those of four others, was announced by his financial group PPF.
An investigation into the crash has been launched by the National Transportation Safety Board.
Mr Kellner and his group had been on a heli-skiing trip – which involves off-trail, downhill skiing or snowboarding reached by helicopter – instead of a ski lift.
The 56-year-old businessman, whose net worth has been estimated at $17.5bn by Forbes, was aboard an Airbus AS350 B3 helicopter when it went down near Knik Glacier.
Officials say it crashed under unknown circumstances about 50 miles east of Anchorage at 6.35pm on Saturday.
A sixth person on board was in a serious but stable condition on Sunday at an Anchorage hospital, Alaska State Troopers said.
They said in a statement that they received a report of an overdue helicopter and the location of possible crash debris on Saturday night.
The others killed were identified as Gregory Harms, 52, of Colorado; Benjamin Larochaix, 50, also of the Czech Republic; and two Alaskans, Sean McMannany, 38, of Girdwood, and the pilot, Zachary Russel, 33, of Anchorage.
The five passengers included three guests and two guides from Tordrillo Mountain Lodge, company spokesperson Mary Ann Pruitt said.
Mr Kellner made his first fortune in the 1990s through the launch of an investment fund that he used to buy a controlling stake in the country’s largest insurance company.
He bought a major European broadcast network, Central European Media Enterprises, for $1.1bn last October, prompting fears in the Czech Republic that the network might lose independence.
Mr Harms was a pioneering heli-ski guide in Alaska and worked for many years at the lodge, Ms Pruitt said.
“Greg was one of the most experienced guides in the business,” she said in an email to the Associated Press.
He also founded a heli-ski company that led trips across the world.
Mr McMannany had been a guide for over 10 years, and was with the lodge for the last five, she said. He was also an avalanche instructor and an experienced mountain guide on Denali, North America’s tallest peak.
She added that Mr Kellner and Mr Larochaix “were loyal and frequent” guests at the lodge.
Mr Russel was a pilot for Soloy Helicopters, a Wasilla-based company that is contracted by the lodge to provide transportation, Ms Pruitt said.
“This news is devastating to our staff, the community in which we operate, and the families of the deceased,” a statement released by the lodge said.
It added that it was the first time in its 17 years in business “we’ve had to face an event of this measure”.
The company website bills itself as the longest operating heli-skiing lodge in Alaska, promising deep powder, pristine runs on some of the best mountain terrain in the world, with packages costing from $15,000 (£10,897) per person.
“An unparalleled alpine adventure is only a helicopter ride away,” the website says.