French authorities say a Chinese magnate, his 12-year-old son and two others died in a helicopter crash as they toured Bordeaux vineyards the businessman had recently purchased.

Vincent Corbel of the regional gendarme service said Monday that emergency workers recovered the boy's body and most of the helicopter from the Dordogne River, but are still searching for the others. He said the reason for the Friday night crash is unclear.

Corbel said the former owner of the Chateau de la Riviere vineyards, James Gregoire, owned the helicopter and appeared to have been piloting it.

Lam Kok, who headed Hong Kong-based company Brilliant Group, drew attention in the French media when he bought the chateau, one of a string of Chinese purchases of French vineyards in recent years.