Among the 22 on board was British tycoon Mike Lynch, who celebrated his recent acquittal from fraud charges in the United States.

Divers and an underwater drone are searching for six people, including a UK tech tycoon and an international banker, who are believed to have been trapped when a luxury superyacht sank off Sicily.

Among the six missing people were technology entrepreneur Mike Lynch and his 18-year-old daughter Hannah, as well as Jonathan Bloomer, the chief executive of Morgan Stanley International, and his wife Judy.

On Tuesday, police divers resumed the search for the six people believed to be trapped in the hull of the British-flagged 56-metre (185-foot) yacht named Bayesian.

The yacht was anchored with ten crew members and twelve passengers on board when it was hit by a mini-tornado in the shape of a waterspout before dawn on Monday morning.

Fifteen people, including a woman and her one-year-old baby, were rescued. The body of a man – reportedly the yacht’s cook, who was from Antigua – was found.

The passengers were guests of Lynch – sometimes referred to as Britain’s Bill Gates – to celebrate his acquittal in a massive fraud case in the United States.

Lynch was acquitted in June of fraud and conspiracy charges in a U.S. federal trial related to Hewlett Packard’s $11 billion acquisition of his company, Autonomy Corp.

The sailboat’s resting place lies about 50 meters underwater – a depth that required special precautions that made the job difficult. Salvage teams said they were working in 12-minute shifts, which slowed their efforts to reach the wreck’s tight interior.

The yacht was anchored about a kilometer offshore when a storm hit before 4 a.m. Monday morning. Civil defense officials believe the vessel was hit by an overwater tornado, known as a waterspout, and sank quickly.

The Giornale di Sicilia website showed grainy footage from coastal surveillance cameras showing the illuminated 75-metre-high mast of the Bayesian weathering the storm and then disappearing within a minute.

The captain of the yacht survived; prosecutors reportedly wanted to question him.

Karsten Borner, captain of the Sir Robert Baden Powell, which rescued the 15 survivors who managed to get into a lifeboat, said he was close enough to see the Bayesian when the storm hit.

“A moment later she was gone,” Borner said. “They said they landed flat on the water and sank in two minutes,” he added, quoting the survivors.

The rotating search teams, each made up of two specialized cave divers, worked Tuesday to open access points to get into the wreck, which lies at a depth far beyond what most recreational divers are allowed to reach. They used a remotely operated underwater vehicle (ROV) to assist in the search.

The divers have not yet been able to access the cabins below deck because they were blocked by furniture that had shifted during the violent storm.

Rescue teams believe the six missing people are in these cabins because the storm hit at a time when most of them were sleeping, but teams were unable to verify their presence there through the portholes.

Charlotte Golunski, who survived the accident, said she briefly lost her footing in the water with her one-year-old daughter Sofia but managed to keep her above the waves until a lifeboat inflated and they were both taken to safety, Italian news agency ANSA reported.

The father, identified by ANSA as James Emslie, also survived, as did Lynch’s wife Angela Bacares. Hannah Lynch, the couple’s 18-year-old daughter, is missing.

Built in 2008 by Italian company Perini Navi, the yacht was available for charter and featured a massive 75-metre (246-foot) aluminium mast, one of the tallest in the world.