Divers searching the wreck of a superyacht that sank off Sicily recovered at least one body Wednesday, as the search continued for more missing passengers and questions intensified about why the sailboat sank so quickly.

Divers and rescue crews unloaded a body bag from one of the rescue vessels that pulled into port at Porticello. The discovery confirmed that the operation to search the wreckage on the seabed 50 meters (165 feet) underwater was a recovery one, not a rescue.

The Bayesian, a 56-meter (184-foot) British-flagged yacht, went down in a storm early Monday as it was moored about a kilometer (a half-mile) offshore. Civil protection officials said they believed the ship was struck by a tornado over the water, known as a waterspout,and sank quickly.

Fifteen people escaped in a lifeboat and were rescued by a nearby sailboat. One body was recovered Monday — that of the ship’s Antigua-born chef, Recaldo Thomas.

Six people remained unaccounted for, including British tech magnate Mike Lynch, his 18-year-old daughter and associates who had successfully defended him in a recent U.S. federal fraud trial.