The Indonesian submarine ship that went missing off the coast of Bali 53 crew members aboard has sunk, AFP reported on Saturday, quoting the country’s navy. “We have raised the status from submiss to subsunk,” Indonesian Navy chief Yudo Margono told reporters.

Earlier search teams had recovered debris believed to be from the submarine, Reuters reported. Margono said that the retrieved items could not have come from another vessel. He said the hunt for the submarine and sailors would continue, but warned that deep waters made the recovery effort “very risky and difficult”.

Navy officials displayed several retrieved items including a piece of the submarine’s torpedo system, a bottle of grease used to lubricate its periscope and a prayer mat. Margono said that the items would not have come outside the submarine if there was no external pressure or without damage to its torpedo launcher, AFP reported.

The KRI Nanggala 402 went missing on Wednesday as it prepared to conduct a torpedo drill, with the head of the Indonesian submarine fleet aboard. On Friday night, officials had said that it was left with enough air to last until around dawn on Saturday, Reuters reported

A total of 24 navy and other ships and a patrol plane were mobilised for Friday’s search with a focus on the area where an oil slick was found after the submarine disappeared. Rescuers made similar massive searches in the past two days.

The diesel-electric powered submarine could withstand a depth of up to 500 metres but anything more could be fatal, Navy spokesperson Julius Widjojono had said, according to Reuters. The Bali Sea can reach depths of more than 1,500 metres.

An Indonesian defence expert, Connie Rahakundini Bakrie, said there was a possibility the crew could still be found alive. “But if the submarine is in a 700-metre sea trough, it will be difficult for them to survive because underwater pressure will cause cracks and ruptures of the steel hull,” he added.

Indonesian President Joko Widodo said the country’s main priority was the safety of 53 crew. “To the family of the crew members, I can understand your feelings and we are doing our best to save all crew members on board,” he said in a televised address.

India to send critical search equipment: Report

India on Saturday will fly critical search equipment to Indonesia to locate the missing submarine, the Hindustan Times reported, quoting unidentified officials.

“Intervention system of the second deep submergence rescue vessel (DSRV) will be airlifted to Indonesia by the Indian Air Force on Saturday,” an official told the newspaper. “This system can be used to locate the submarine.”

Earlier on Thursday, the Indian Navy had dispatched a DSRV by sea to help the Indonesian Navy with its search and rescue efforts. The rescue vessel is being ferried by offshore supply vessel Sabarmati, and could take almost a week to reach the location.

Defence minister Rajnath Singh had also asked the Indian Air Force to examine the feasibility of induction of the deep submergence rescue vessel intervention system by air. The Indian Navy’s DSRV system can locate a submarine up to 1,000 metres underwater, according to the Hindustan Times.

Meanwhile, the United States also offered support. On Friday, the Pentagon said US Defense Secretary Lloyd Austin had spoken with his Indonesian counterpart and offered additional support, which could include undersea search assets.

White House national security adviser Jake Sullivan told Indonesian Foreign Minister Retno Marsudi on Thursday the “United States would do everything possible to support Indonesia’s search and rescue effort,” a spokesperson said, according to Reuters.