The Czech Republic’s richest man, Petr Kellner, whose financial group has deep roots across Eastern Europe and Central Asia, has died in a helicopter crash in Alaska.

“With great sadness, PPF announces that on March 27, 2021, majority shareholder of PPF Mr. Petr Kellner tragically passed away in a helicopter accident in the Alaskan mountains,” the group said in a short statement on March 29.

It said that the crash, which claimed five lives, was under investigation. Alaska State Troopers said one survivor was listed in serious but stable condition.

U.S. media has reported that the accident occurred when the helicopter, which was taking the group on a heli-skiing excursion, crashed near the Knik Glacier in Alaska.

The 56-year-old Kellner, the world’s 68th-wealthiest person according to Forbes, died along with another guest of the Tordrillo Mountain Lodge, Benjamin Larochaix, also of the Czech Republic, two of the lodge’s guides, and the pilot of the helicopter, the reports said, citing officials.

Kellner, whose wealth was estimated by Forbes magazine at $17.5 billion, started his business selling copy machines and founded the PPF Group investment company with partners in 1991, two years after the fall of communism in the former Czechoslovakia, to take part in the country’s scheme to privatize state-owned firms.

PPF Group went on to grow in finance, telecommunications, manufacturing, media, and engineering in businesses spanning mainly Europe, Asia, and the United States. Its assets amounted to nearly $52 billion by mid-2020.

The group includes Home Credit International, the world’s largest nonbanking consumer lender with extensive activities on the Russian and Chinese markets.

PPF last year acquired the CME media group operating TV companies in Central and Eastern Europe. In 2018, it became the sole owner of Telenor’s telecommunications assets in Hungary, Bulgaria, Montenegro, and Serbia.

The group has donated millions of respirators and masks and thousands of coronavirus testing kits to help countries in the coronavirus pandemic, according to Czech media reports.

Czech Prime Minister Andrej Babis offered his condolences to Kellner’s family, saying on Twitter: “Unbelievable tragedy. I am very sorry.”

Kellner’s daughter Anna Kellnerova, a two-time Czech junior equestrian show-jumping champion, said his funeral will be held “with only close family members.”

With reporting by The New York Times, AP, Reuters, and AFP