British tech tycoon Mike Lynch and his daughter are among the six people missing after a luxury yacht sank off the coast of Sicily in the early hours of Monday morning.
The 56m (183ft) vessel was carrying 22 people – 10 crew and 12 passengers – including British, American and Canadian nationals.
Emergency services rescued 15 people, including a one-year-old British girl.
According to local media reports the yacht, sailing under the name Bayesian, sank after encountering a heavy storm overnight that caused waterspouts, or rotating columns of air, to appear over the sea.
Mr Lynch, known by some as “the British Bill Gates”, co-founded software company Autonomy, which was later bought by tech giant Hewlett-Packard for $11bn (£8.6bn).
Witnesses told Italian news agency Ansa that the Bayesian’s anchor was down when the storm struck, causing the mast to break and the ship to lose its balance and sink off the coast of village Porticello, near Sicilian capital Palermo.
Divers have identified a wreckage 50m below the water’s surface and are searching for those missing.
The director general of Sicily’s civil protection agency, Salvatore Cocina said that Mr Lynch, his daughter Hannah Lynch and the yacht’s chef, Ricardo Thomas, are among the missing.
He said the search, involving caving and rescue diving teams, will continue overnight.
The body of one man has been found outside of the wreckage. His nationality has not been confirmed.
