NASSAU, Bahamas (AP) — Rescuers spotted floating debris and an oil sheen Sunday as US crews continue an intensive search off the south-eastern Bahamas for a US cargo ship with 33 people on board. The company that owns the ship said a container that appears to belong to the vessel had been found as well.

The ship, the 790-foot El Faro, has not been heard from since it lost power and was taking on water in fierce seas churned up by Hurricane Joaquin.

By early Sunday afternoon, the US Coast Guard said its aircrews spotted “life jackets, life rings, containers and an oil sheen” in the sprawling search area but they have not yet been able to confirm whether the debris and oil is from the El Faro. On Saturday, the Coast Guard said it located an orange life ring from the cargo ship that emitted a distress ping Thursday, but then went silent.

The missing vessel’s owner, TOTE Maritime Puerto Rico, said a contracted tugboat and another of its ships had found a container that appears to be from the El Faro. But “there has been no sighting of the El Faro or any life boats”, company president Tim Nolan said in a statement.

US Navy and Air Force planes and helicopters were helping Coast Guard crews looking for the ship across a broad expanse of the Atlantic Ocean around Crooked Island, which the El Faro was passing as the storm turned into a powerful Category four hurricane.

TOTE Maritime Puerto Rico told family members of the crew gathered at a union hall in Jacksonville, Florida, not to be discouraged after news of the life ring found Saturday was circulated.

Laurie Bobillot, whose daughter, Danielle Randolph, is a second mate on the El Faro, said Sunday she was trying not to lose hope after nearly four days anxiously waiting for news of the ship.

“We’ve got to stay positive,” said Bobillot, of Rockland, Maine. “These kids are trained. Every week they have abandon ship drills.”

Both she and Robin Roberts, whose stepson Mike Holland is an engineer on the El Faro, said they had faith in the skill of the ship’s captain, whose name the company has declined to release.

“This is a top-notch captain. He’s well-educated,” Bobillot said. “He would not have put the life of his crew in danger, and would not have put his own life in danger, had he known there was danger out there. He had the best intentions. He has a family too, and he wanted to go home to them too. That storm just came up way too fast.”

Hurricane Joaquin moved out of the Bahamas and was nearing the mid-Atlantic territory of Bermuda on Sunday afternoon as a weakening Category three storm. Rough weather had initially hampered the search, but conditions had improved enough by Sunday for the Coast Guard to dispatch one of its cutters, the Northland, to aid the aerial search. Two other cutters were on their way.

“Our hope is that we can really saturate that area better than yesterday,” Petty Officer First Class David Schuhlein, a Coast Guard spokesman.

By early Sunday afternoon, weather conditions had improved significantly, with rescuers dealing with one-foot seas, 15-knot winds and unrestricted visibility, according to the Guard.

The El Faro departed from Jacksonville, Florida on September 29, when Joaquin was still a tropical storm, with 28 crew members from the United States and five from Poland. The ship was heading to Puerto Rico on a regular cargo supply run to the US island territory when it ran into trouble. It was being battered by winds of more than 130 mph and waves of up to 30 feet (nine metres).

The crew reported it had taken on water and was listing 15 degrees but said it was “manageable”, according to its owner.

In a statement, TOTE Maritime Puerto Rico said it authorised the sailing “knowing that the crew are more than equipped to handle situations such as changing weather”.

As more floating debris was spotted Sunday, the company said it’s “thoughts and prayers remain with the 33 individuals aboard the ship and their families”.