The helicopter crashed into the Dordogne river Friday during a celebration of the Chinese businessman's investment, the BBC reported.
The passengers are feared dead, but authorities have not been able to locate all the missing people due to a strong current in the river, the BBC reported.
The helicopter was carrying Kok, his 12-year-old son, an interpreter and the vineyard's former owner, James Gregoire, who recently sold the property to the 46-year-old Chinese businessman.
Gregoire had offered to give Kok a tour of the estate in the helicopter following a news conference.
Kok had planned to turn the 160-acre property into a wine and tasting center, the BBC said.
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