PALERMO, Sicily — One man died and six people were missing, including British tech entrepreneur Mike Lynch and his daughter, after a luxury yacht was struck by an unexpectedly violent storm and sank off Sicily early on Monday.

The British-flagged "Bayesian", a 56-metre-long (184-ft) sailboat, was carrying 22 people and was anchored just offshore near the port of Porticello when it was hit by ferocious weather, the Italian coast guard said in a statement.

Eyewitnesses said the yacht vanished quickly beneath the waves shortly before dawn. Fifteen people escaped before it went down, including Lynch's wife, Angela Bacares, who owned the boat, and a one-year-old girl.

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The names of the dead and missing were not immediately released, but a person familiar with the rescue operation confirmed that Lynch and his 18-year-old daughter, Hannah, were not accounted for.

Salvatore Cocina, head of the Civil Protection in Sicily said Jonathan Bloomer, chairman of Morgan Stanley International (MS.N) and Chris Morvillo, a lawyer at Clifford Chance were also among the missing people.

Italian media said the dead man was the yacht's onboard chef.

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Morgan Stanley did not immediately respond to a phone call and email seeking comment after hours. Clifford Chance did not return a request for comment.