British tech giant Mike Lynch, his lawyer and four other people are among those missing after their luxury superyacht sank during a freak storm off Sicily, Italy's civil protection and authorities say.
Lynch's wife and 14 other people – including a one-year-old girl – survived but the entrepreneur was among the six people who remained unaccounted for after their chartered sailboat sank when a waterspout struck the area overnight, Salvo Cocina of Sicily's civil protection agency said.
The sailboat overturned sometime before 5am on Monday (1pm AEST) off the port of Porticello, near Palermo in southern Italy, where it was anchored.
Lynch founded business software firm Autonomy and ran it as CEO until computer giant Hewlett Packard bought it in 2011.
One body has been recovered, and police divers were trying to reach the hull of the ship, which was resting at a depth of 50 metres.
The yacht had a crew of 10 people and 12 passengers, including British, American and Canadian nationalities, the Italian coast guard said.
A sudden fierce storm had battered the area overnight, and struck the place precisely where the 56-metre (184-foot) British-flagged Bayesian had been moored.
"They were in the wrong place at the wrong time," said Cocina, noting that another superyacht nearby wasn't as badly damaged and was able to rescue some of the 15 survivors.
The Bayesian was known for its single 75-metre mast, one of the world's tallest made of aluminium and which was lit up at night, just hours before it sank. Online charter sites list it for rent for up to €195,000 ($321,000) a week.
One of the survivors, identified only as Charlotte, said she had momentarily lost hold of her one-year-old daughter Sofia in the water, but then managed to hold her up over the waves until a lifeboat inflated and they were both pulled to safety, Italian news agency ANSA reported, quoting the mother.
A trawler captain, Karsten Borner, said there had been strong gusts of wind and his crew had had to start the engine to keep their ship in the right anchor position.
"After the storm was over, we noticed that the ship behind us was gone," he said.
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Borner told reporters on the coast how he helped rescue the survivors.
"We saw a red flare so my first mate and I went to the position, and we found this life raft drifting … with 15 people inside," he said.
Borner said four people were injured and another three seriously injured. The crew brought the survivors to his ship and called the Coast Guard.
"It was a big disaster," he said.
Eight of the 15 people rescued and taken to shore at Porticello were hospitalised. One body was found near the wreck, but six others were unaccounted for, said Luca Cari, a spokesperson for the Italian fire rescue service.
Rescue crews located the vessel at a depth of 50 metres off Porticello and deep-water police divers were trying to access the hull, Cari said. The operations, which were visible from shore, involved helicopters and rescue boats from the coast guard, fire rescue and civil protection service.
Fisherman Francesco Cefalu' said he had seen a flare from shore about 4.30am (12.30pm AEST) and immediately set out to the site but by the time he got there, the Bayesian had already sunk, with only cushions, wood and other items from the superyacht floating in the water.
"But for the rest, we didn't find anyone," he said from the port hours later.
He said that he immediately alerted the coast guard and stayed on site for three hours, but didn't find any survivors.
"I think they are inside, all the missing people."
He said he had been up so early to check the weather to see if he could go fishing, and surmised that a sudden waterspout had struck the yacht.
"It could be that the mast broke, or the anchor at the prow pulled it, I don't know," he said.
Who is Mike Lynch?
Lynch turned ground-breaking research at Cambridge University into the foundation of Autonomy, which became Britain's biggest software company and a member of the blue-chip FTSE 100 index.
The man once hailed as Britain's king of technology was earlier this year cleared of charges alleging he orchestrated a fraud and conspiracy leading up to the $US11 billion ($16.4 billion) HP deal, which turned into a costly albatross for the Silicon Valley pioneer.
He was lauded by academics and scientists and asked to advise the British government on technology and innovation.
The Autonomy acquisition was meant to fuel HP's software business. Instead, it spawned a series of bitter and expensive legal battles. HP largely won a civil lawsuit against Lynch and Hussain in London in 2022, though damages have not yet been decided. The company is seeking $US4 billion ($6 billion).
The seven who weren't rescued included one crew member and six passengers, the coast guard said.
The yacht, built in 2008 by the Italian firm Perini Navi, can accommodate 12 passengers in four double cabins, a triple and the master suite, plus crew accommodations, according to Charter World and Yacht Charters.
The vessel, which previously was named Salute when it flew under a Dutch flag, featured a sleek, minimalist interior of light wood with Japanese accents designed by the French designer Remi Tessier, according to descriptions and photos on the charter sites.
- Reported with CNN