British technology magnate Mike Lynch and his 18-year-old daughter are among six people missing after a luxury yacht sank off the coast of the Italian island of Sicily in the early hours of Monday.

The 56 m long ship had 22 people on board, including British, American and Canadian citizens. 15 people were rescued, including a one-year-old British girl. The authorities continued to search for the ship into the night.

Local media reported that the yacht, named Bayesian, capsized at around 05:00 local time. after we had been caught in a severe storm overnight, which led to the formation of waterspouts, i.e. rotating columns of air, over the sea.

Mr Lynch, described by some as “the British Bill Gates”, was a co-founder of the software company Autonomy, which later bought by technology giant Hewlett-Packard for $11 billion (£8.6 billion).

Witnesses told Italian news agency Ansa that the Bayesian’s anchor was down when the storm hit, causing the mast to break and the ship to lose its balance and sink off the coast of the village of Porticello, near the Sicilian capital of Palermo.

A waterspout resembles a tornado and can form over oceans, seas or large lakes.

Divers have identified a wreck 50 meters below the water surface and are searching for the missing people.

The director general of the Sicilian civil protection agency, Salvatore Cocina, told the BBC that Mr Lynch, his daughter Hannah Lynch and the yacht’s cook were among the missing.

He said the search, involving caving and rescue diving teams, would continue throughout the night.

The body of a man was found outside the wreckage. His nationality has not been confirmed.

BBC Verify reviewed company records and found that Bayesian’s ownership is linked to Mr Lynch’s wife, Angela Bacares.

Sources familiar with the matter confirmed to the BBC that Ms Bacares was rescued.

After the storm broke out, 15 people were able to reach safety.

The news agency Ansa reported that a 35-year-old mother held her one-year-old daughter in the sea in her arms.

The woman who is as locally known as Charlotte Golunski said: “I lost the little girl in the sea for two seconds, then I immediately hugged her again in the midst of the roaring waves.

“I held them close to me while the sea stormed. Many screamed.

“Luckily, the lifeboat was inflated and eleven of us managed to get on board.”

The baby is doing well and the mother has received stitches, the agency said.

She added that she was on the boat with her husband, who is also doing well, and colleagues from a London company.

A doctor at the Di Cristina hospital in Palermo, where some of the survivors were taken, said they were “very tired” and “constantly asking about the missing people”.

Dr. Domenico Cipolla told Reuters: “We have given this information to the survivors, but they talk and cry all the time because they have realized that there is little hope of finding their friends alive.”

Survivors said the trip was organised by Mr Lynch for his work colleagues.

First, a Dutch ship sailing nearby rescued survivors from the waves and cared for them until rescue workers arrived.

Captain Karsten Borner said that after the storm passed, the crew noticed that the yacht that had been behind them had disappeared.

“We saw a red flare, so my first mate and I went to the position and found this drifting life raft,” he told Reuters.

There were 15 survivors on board the life raft, three of whom were “seriously injured,” he said.

A local fisherman told Reuters he saw people being rescued by a dinghy sent from another yacht.

The captain of a local fishing vessel said he saw debris floating in the sea, including cushions from the deck.

Footage from the wreck site showed helicopters circling above several Coast Guard vessels as divers descended into the water in bright orange.

Eight of the rescued people are being treated in hospital, the Italian coast guard said.

The western half of the Mediterranean has been hit by severe storms since the middle of last week.

During the night from Sunday to Monday, a bad weather front passed along the north coast of Sicily.

BBC weather forecaster Matt Taylor said: “A waterspout is a tornado that has occurred over water rather than land.”

“They can form at the base of cumulonimbus/thunderstorm clouds during severe storms.

“Turbulence and wind blowing in slightly different directions around the cloud can cause rotation under the cloud base and the formation of a fountain.

“Like tornadoes, they bring powerful winds, but instead of stirring up dust and debris, they create a mist of water around the rotating column of air.”

The British Foreign Office said it was providing support to a number of British nationals and their families following an incident in Sicily. The British Marine Accident Investigation Branch is also sending a team of inspectors to make a “preliminary assessment” of the sinking of the British-registered boat.

The Bayesian The registered owner is listed as Revtom Ltd. The superyacht can accommodate up to 12 guests in six suites.

The name of the yacht is said to be based on Bayes’ theory, which was also the basis of Mr Lynch’s doctoral thesis.

Mr Lynch’s wife, Mrs Bacares, is listed as the sole owner of Revtom, which is registered in the Isle of Man.

A spokesman for Camper and Nicholsons International, the company that manages the 2008-built boat, told BBC Verify: “Our priority is to assist with the ongoing search and provide any necessary assistance to the rescued passengers and crew.”

Mr Lynch sold his company Autonomy to American computer giant Hewlett-Packard (HP) in 2011 for $11 billion (£8.6 billion).

But after the spectacular takeover, Lynch was mired in a bitter legal battle for over a decade. In June, he was acquitted in the US of several fraud charges for which he had faced a prison sentence of two decades.

The yacht’s sinking occurred on the same day that the lawyer for Lynch’s co-defendant in the fraud case, Stephen Chamberlain, confirmed his death after he was hit by a car in Cambridgeshire on Saturday.

Additional reporting by Joshua Cheetham of BBC Verify