British technology tycoon Mike Lynch and his daughter are among six tourists missing after a luxury yacht sank in a tornado off the coast of Sicily, sources said.
A body, believed to be that of the vessel’s cook, has been found and police divers are trying to reach the hull of the ship, which is resting at a depth of 50 metres.
Four of the missing passengers are British and two are American, Italian news website la Reppublica stated.
Sicily’s civil protection agency told the BBC that 18-year-old Hannah Lynch was among those missing with her father, along with the yacht’s chef, Ricardo Thomas.
The yacht was carrying 10 crew members and 12 passengers.
Fifteen people including Mr Lynch’s wife, Angela Bacares, were rescued, according to local media.
The British-flagged superyacht, named Bayesian, capsized at about 5am local time off the coast of Palermo when the area was hit by a tornado.
Mr Lynch, who founded software giant Autonomy in 1996, was made an OBE for services to enterprise in 2006.
In June, he was cleared of conducting a massive fraud relating to an 11 billion dollar (£8.64 billion) sale to US company Hewlett Packard.
A spokesperson for Mr Lynch said there was no comment.
The yacht sank as a fierce storm battered the area overnight.
The daily Il Giornale di Sicilia newspaper reported that the vessel had mostly British passengers on board, but also people from New Zealand, Sri Lanka, Ireland and British-French citizens.
Salvo Cocina of Sicily’s civil protection agency said: “They were in the wrong place at the wrong time.”
One of the survivors, British tourist Charlotte Emsley, told la Reppublica she held her one-year-old daughter, Sofia, to stop her from drowning.
She said: “I held her afloat with all my strength, my arms stretched upwards to keep her from drowning.
“It was all dark. In the water I couldn’t keep my eyes open. I screamed for help but all I could hear around me was the screams of others.”
Charlotte and Sofia are being treated in hospital, as is Sofia’s father, James Emsley.
Karsten Borner, captain of a nearby boat, told journalists those missing included the Bayesian’s owner and a child, news agency Reuters reported.
He said his crew took on board some survivors who were on a life raft, including three who were seriously injured.
Fisherman Francesco Cefalu said he sailed from the shore to the scene after seeing a flare at about 4.30am, but by the time he arrived Bayesian had already sunk, with only items such as cushions and wood floating in the water.
He added: “I think they are inside, all the missing people.”
A spokesman for the Foreign, Commonwealth and Development Office (FCDO) said: “We are in contact with the local authorities following an incident in Sicily, and stand ready to provide consular support to British nationals affected.”
The Marine Accident Investigation Branch said four of its inspectors were being deployed to Palermo.
A basic assessment of the scene will be made by the team, with no investigation launched at this stage, the PA news agency understands.
Bayesian completed a number of sailings in recent days, calling at various ports in Sicily, according to ship-tracking website VesselFinder.
The superyacht can accommodate up to 12 guests in six suites, and is listed for rent for up to 195,000 euros (£166,000 ) a week.
She was built in 2008 by Italian company Perini Navi.
Her registered owner is listed as Revtom Ltd, which is based on the Isle of Man.
Mr Lynch is of Irish heritage – his father was a fireman from Co Cork, and his mother was a nurse from Co Tipperary.
In a 2015 radio interview, Mr Lynch confirmed that he was born in Ilford in London, despite a number of reports that he was born in Ireland and raised in England.
He said during the same interview that he spent childhood summers in Carrick-On-Shannon and Tipperary and has family who still live there.