Deep-sea divers with Italy’s firefighter corps resumed their search on Tuesday morning for six passengers — including a British software mogul and his daughter — who are missing after a yacht sank off the coast of Sicily the previous day.

There were 22 people on board the British-flagged Bayesian, a 180-foot sailing yacht, which was anchored offshore near the port of Porticello when it was hit by what eyewitnesses described as a waterspout, a small tornado on water, during a sudden and very violent storm.

Fifteen people managed to find safety on a raft and were rescued by the captain of a nearby sailing cruise ship.

The body of the ship’s cook was recovered on Monday, but several people are still unaccounted for, according to to Salvatore Cocina, an official with Sicily’s civil protection agency: Mike Lynch, a British technology entrepreneur, and his daughter Hannah; Jonathan Bloomer, chairman of Morgan Stanley International, and his wife; and Christopher J. Morvillo, a lawyer at Clifford Chance, and his wife.

Mr. Lynch was acquitted of fraud in a trial in the United States in June, ending a high-profile, decadelong legal battle against accusations that he had defrauded Hewlett-Packard when he sold it his company, Autonomy, for $11 billion.

The news about Mr. Lynch came just days after Stephen Chamberlain, a former vice president of finance at Autonomy and Mr. Lynch’s co-defendant at his fraud trial, was fatally struck by a car on Saturday while out for a run, his lawyer, Gary S. Lincenberg, said in a statement.