A British mother on board a yacht which sank off the coast of Sicily has described holding her baby girl above the surface of the sea to save her from drowning.

The mother, named locally as Charlotte Golunski, her partner and one-year-old daughter are reported to be among 15 people to have been rescued from the luxury yacht Bayesian early on Monday.

Six people – including British tech entrepreneur Mike Lynch – are missing with one man found dead outside the wreckage.

The 56m (183ft) vessel, which was carrying 10 crew and 12 passengers, sank half a mile off the coast of Palermo after encountering a heavy storm overnight that caused waterspouts, or rotating columns of air, to appear over the sea.

Charlotte told Italian newspaper La Repubblica her family survived because they were on deck when the yacht sank.

She said they were woken by “thunder, lightning and waves that made our boat dance”, and it felt like “the end of the world” before they were thrown into the water.

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“For two seconds I lost my daughter in the sea then quickly hugged her amid the fury of the waves,” the paper quoted her as saying.

Charlotte said she held her baby “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,” she added.

A lifeboat inflated and she said 11 people were able to climb in. All three of the family were unharmed and taken to hospital for check-ups.

Karsten Borner, captain of a nearby boat, said his crew took on board some survivors on a life raft, including three who were seriously injured.

Describing the moment, the storm hit, he told Italian news outlet Rai the superyacht tipped to its side and sank within “a few minutes”

“It all happened in really little time,” he said.

A local fisherman, Giuseppe, told Reuters he was on board a motorboat when he saw “mats and T-shirts floating in the sea”.

Another witness, Fabio Cefalù, captain of a trawler, says he was about to go out on a fishing trip when he saw flashes of lightning so he stayed in the harbour.

“At about 4:15am we saw a flare in the sea,” he said, according to the EVN news agency reports.

“We waited for this waterspout to pass. After 10 minutes we went out to the sea and we saw cushions and all the rest of the boat [that had sunk], and everything which was on the deck, at sea. However, we did not see any people in the sea.”

Another fisherman described seeing the yacht “sinking with my own eyes”.

Speaking to the newspaper Giornale di Sicilia, the witness said he was at home when the tornado hit.

“Then I saw the boat, it had only one mast, it was very big,” he said.

Shortly afterwards he went down to the Santa Nicolicchia bay in Porticello, the fishing village near Palermo where the disaster unfolded, to get a better look at what was happening.

He added: “The boat was still floating, then all of a sudden it disappeared. I saw it sinking with my own eyes.”