A luxury superyacht sailboat carrying foreign tourists has capsized and sunk off Sicily in bad weather. One body has been found, six people are missing and 15 people have been rescued, authorities said.

UK tech tycoon Mike Lynch is among the missing, according to reports. He was acquitted in June by a San Francisco jury of fraud charges linked to the sale of his software company, Autonomy, to Hewlett-Packard for $11 billion (€10 billion) in 2011.

The ship, owned by Lynch’s family, overturned around 5am on Monday off the port of Porticello, where it was apparently anchored.

It had a crew of 10 people and 12 passengers, including British, American and Canadian nationalities, the Italian coast guard said. Local media said a sudden fierce storm, including tornados over water known as waterspouts, had battered the area overnight but skies were clear and seas calm by Monday morning.

The 56-metre British-flagged “Bayesian” was known for its unusually single 75-metre mast, one of the world’s tallest made of aluminium. Online sites list it for charter for up to €195,000 a week.

Some of the survivors have already been identified. One of them is Angela Bacares, Lynch’s wife.

Another survivor, identified only as Charlotte, said she had momentarily lost hold of her 1-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.

Eight of the people initially rescued and taken to shore at Porticello, near Palermo, 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.

The nationality of the man who died has not yet been identified.

Rescue crews located the ship at a depth of 50 metres off Porticello and experienced 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 the shore at around 4:30am and immediately set out to the site. However, 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.

The seven who had not made it so far 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 the “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 sites.