The twin brother of the Morgan Stanley chairman missing after the Bayesian superyacht sank off the coast of Italy said there may be air pockets in the sunken vessel keeping those yet to be found alive.

Morgan Stanley Bank International chair Jonathan Bloomer’s twin brother, Jeremy, said their family is anxiously awaiting news on his sibling’s condition after the banker and his wife, Judy, went missing when the superyacht capsized and sank during a violent storm Monday.

“They’re still going down to the wreck, they can’t get through at the moment because of the debris in the way,” Jeremy Bloomer told BBC.

“It’s a slow process, and it will take time. There might be air pockets but we don’t know,” he added.

Jeremy said the only news the family had received was confirmation that his brother was on the yacht, but that the family is doing the best they can to support each other.

“He was my elder by half an hour, so, it means a lot when you lose a twin brother. We’ll still wait and see, so it’s fingers crossed,” he said.

In addition to the Bloomers, British tech tycoon Mike Lynch, his 18-year-old daughter Hannah, top New York City lawyer Christopher Morvillo and his wife, Neda, a jewelry designer, are also still missing.

Morvillo’s wife, Neda, a jewelry designer, is also one of the six passengers still missing, officials said. 

One person, the ship’s on-board chef, was killed when the yacht capsized off the coast of Sicily early Monday morning.

Captain James Catfield, who piloted the 184-foot, British-flagged ship, was among the 15 crew members and passengers to survive.

While authorities have said the chances of passengers surviving the disaster were very small, they did not rule out the possibility.