A super yacht with 22 people onboard sank off the coast of Sicily after being struck by an unexpectedly violent storm off the region capital Palermo. Fifteen people were rescued from the 56-metre sailing boat Bayesian by coastguard patrol boats and firefighters, including a one-year-old child, but one man died and six people are still missing. The 56-metre-long sailboat, which was British registered, sank with 22 people on board shortly before sunrise, the coast guard said in a statement.

The missing people were of British, American and Canadian nationality. "The wind was very strong. Bad weather was expected, but not of this magnitude," a coast guard official in Palermo told Reuters.

Eight of the 15 people rescued, including a one-year-old child, were transferred to local hospitals. All were in a stable condition. The coast guard said the boat had been found at a depth of 49 metres and that divers were inspecting the wreck.

Prosecutors in the nearby town of Termini Imerese have opened an investigation to look into what had gone wrong. The coast guard named the yacht as the Bayesian, built by Italian shipbuilder Perini in 2008. The luxury ship has an aluminium hull and can carry 12 guests and a crew of up to 10.

The boat left the Sicilian port of Milazzo on August 14 and was last tracked east of Palermo on Sunday evening. Reports said that a waterspout had hit the vessel. A waterspout, which roughly resembles a mini-tornado, is a column that descends from a cloud to form a ro.