JAKARTA, Indonesia — Indonesia's navy on Saturday said it found debris and items likely to have come from a submarine that went missing days ago, meaning the vessel is almost certain to have sunk with its 53 crew members, who are unlikely to have survived.

Speaking at a news conference, Adm. Yudo Margono, the navy chief of staff, declared that the submarine had sunk, citing items found floating near its last known location. Rescuers, he said, found items from the KRI Nanggala-402, a diesel-electric submarine, including a torpedo accessory and prayer rugs.

“With the authentic proof believed to come from the Nanggala, we are escalating the status from a sub-miss to sub-sunk phase,” Margono said. Officials previously categorized the submarine as “missing.”

Search and rescue personnel, Margono said, detected the vessel at 2,788 feet, a depth at which survival of the structure would be near impossible.

Margono did not confirm or comment on the fate of the crew members, and he said rescuers were still working to locate and rescue the crew trapped inside. Officials previously said, however, that the submarine’s oxygen supply would have run out early Saturday.

Officials said the Nanggala could have lost power during a dive and subsequently been crushed by the water pressure as it sank. The Indonesian navy has cleared an American reconnaissance plane, a P-8 Poseidon, to help in the search, along with a warship from Australia.

More resources from Singapore and Malaysia were expected Saturday.

“The rescue team on the ground works hard,” Margono said. But, he added, there is exceptional “difficulty in performing an operation at that depth.”

Other than the objects, searchers also have found an oil spill and detected an unidentified object exhibiting high magnetism at a site about 21 nautical miles north of Bali.

“Our thoughts and prayers are with the Indonesian Navy, their Sailors and all those families who lost loved ones,” Adm. Mike Gilday, the U.S. Navy’s chief of naval operations, tweeted Saturday.

He added: “Despite this tragic loss, it is my hope that we will continue to operate together in support of a free and open Indo-Pacific.”

Since the submarine went missing, relatives have clung to the hope that their loved ones might be discovered alive. The hashtag #PrayForKRINanggala402 has been trending in the country since Friday. The country in recent years has suffered natural disasters and an aviation tragedy, and, most recently, the coronavirus pandemic.

Berda Asmara, the wife of Petty Officer 2nd Class Mes Guntur Ari Prasetya, who was on the submarine, said she has not been able to sleep for three days. She said she spoke to her husband over a video call just 30 minutes before his departure on the Nanggala, on which he had served for a decade.

She has been too distraught, she said, to tell their 8-year old daughter what has happened.

“I don’t know how to explain it to her,” said Asmara, a 33-year old university lecturer in Surabaya. “She keeps asking why I am crying.”

She found out that the submarine was missing, she said, from a WhatsApp group of wives of sailors and crew members on the submarine.

Winny Widayani, the 45-year old wife of Col. Harry Setiawan, said he had been serving with the Nanggala for almost two decades. Her 18-year old son, she said, plans to enlist in the military next year, inspired by his father.

“I know my husband is strong,” Widayanti said. “I believe he will survive and we can be back together.”

Mahtani reported from Hong Kong.