chris cline
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The West Virginia billionaire killed in a helicopter crash off the Bahamas died alongside one of his daughters and some of her pals, friends said.

Chris Cline, a coal tycoon who once dated Tiger Woods' ex-wife, Elin Nordegren, was killed Thursday, a day before his 61st birthday, when the chopper crashed around 2 a.m. shortly after taking off from Grand Cay in the Bahamas, the Register-Herald reported.

The mining entrepreneur's daughter Kameron was among the seven victims on the submerged aircraft, which was discovered overturned two miles off his private island, news station KFSN reported.

Two young adults, his pal, the pilot and a helicopter mechanic were also reportedly aboard the ill-fated flight.

"Prayers for Family and friends of my great friend Chris Cline and his daughter Kameron and her dear friends who we loss (sic) today in a helicopter crash," West Virginia state Sen. Sue Cline wrote on Twitter. "Chris was [an] exceptional human being and we all loved him so much. Such a loss for all 7 aboard today. Our hearts are broken."

The helicopter was headed to Fort Lauderdale due to the possible illness of someone on board — but the pilot "made no request or permission to go" before the flight, according to the Register-Herald.

Bahamian officials said the cause of the crash is under investigation.

"They're attempting ... to first of all go to the helicopter and retrieve any souls that are onboard and start the investigation," Minister of Tourism and Aviation Dionisio D'Aguilar told the Nassau Guardian.

Cline was the founder of coal mining firm Foresight Energy, and was estimated to be worth $1.8 billion at the time of his death, according to Forbes.

He lost his first wife to cancer and his second marriage ended in divorce, according to the Register-Herald. In addition to Kameron, he was the father of three other children, Candice, Alex and Christopher.

Cline started dating Nordegren in 2013 following her highly publicized divorce. Page Six last spotted the on-again, off-again couple together in 2016.