A fifth body has been brought to shore as Italian authorities search for the last person missing from the “Bayesian” superyacht that sank off the coast of Sicily earlier in the week.

A CNN team on the ground saw Italian authorities move the body from a rescue boat to ambulances at the Sicilian port of Porticello early Thursday.

The head of Sicily’s civil protection agency Salvatore Cocina had told CNN on Wednesday that the fifth body had been located on the yacht but had not yet been recovered or identified.

The news comes after four bodies were found by divers on Wednesday, though the identities of those found remain unclear.

The British-flagged vessel, carrying 22 people on board, sank early Monday after its mast, one of the world’s tallest, broke in half during a violent storm. Fifteen people were rescued, with six initially reported missing, and one body recovered Monday – thought to be that of the onboard chef Ricardo Thomas.

The six individuals reported missing are British tech titan Mike Lynch and his 18-year-old daughter, Hannah Lynch; Morgan Stanley International director Jonathan Bloomer and his wife, Judy Bloomer; prominent American lawyer Chris Morvillo and his wife, Neda Morvillo.

Initial reports suggest a small waterspout, which developed over the area the boat was in Siciliy on Monday morning, could have been behind the yacht’s sinking.

Four days in, Italian authorities are still trying to understand how the 56-meter (184-foot) yacht sank so quickly. Separately, the United Kingdom’s Marine Accident Investigation Branch (MAIB) has also opened an investigation, saying on Wednesday that it would deploy a team of four inspectors to Palermo to conduct a preliminary assessment of the scene.

Waterspouts, a type of tornado, are spinning columns of air that form over water, or move from land out to water. They are often accompanied by high winds, high seas, hail and dangerous lightning. While they are most common over tropical oceans, they can form almost anywhere. Waterspouts in Sicily, however, are rare.

Giovanni Costantino, CEO of The Italian Sea Group, which owns the boat’s manufacturer, told Sky News on Wednesday that there was no indication that the design or construction of the boat was at fault in the ship’s sinking.

“This episode sounds like an unbelievable story, both technically and as a fact,” Costantino said.

“Sailing ships, it is well known, are the safest in the most absolute sense. First of all because they have very little surface compared to a yacht facing into the wind. Second, with the structure of the drift keel, they become unsinkable bodies,” he added.

The Bayesian was built in 2008 by the Italian company, Perini Navi.

Unverified security camera footage released on Wednesday appears to have shown the moments that the tornado sank the yacht. As rain pelted down on the port, a grainy video shows the boat being battered by the storm, rocking violently from side to side before capsizing.

CNN