The Indonesian submarine that went missing four days ago was found Sunday in at least three parts on the ocean floor — with all 53 crew members officially declared dead, officials said.

“We received underwater pictures that are confirmed as parts of the submarine,” military chief Hadi Tjahjanto said Sunday of the KRI Nanggala-402, which lost contact on Wednesday.

“With this authentic evidence, we can declare that KRI Nanggala 402 has sunk and all the crew members are dead,” Tjahjanto said.

Soon after the announcement, President Joko Widodo gave a televised address saying that “all Indonesians convey deep sorrow for this tragedy.”

“They are the best sons of the nation, patriots guarding the sovereignty of the country,” Widodo said of the dead crew.

The images were taken by an underwater robot that found the lost submarine lying in at least three pieces on the ocean floor at around 2,750 feet, Adm. Yudo Margono, the navy’s chief of staff, said.

That’s much deeper than the submarine’s collapse depth of 655 feet, at which point water pressure would be greater than the hull could withstand, according to earlier navy statements.

Emergency survival suits normally kept in boxes were found floating underwater, suggesting the crew had tried to put them on during the emergency, Margono said.

Even had they managed to get them on, oxygen supplies likely would have run out by Saturday morning, officials had said.

The exact cause of the submarine sinking remains unclear. The navy previously said an electrical failure could have left the vessel unable to execute emergency procedures to resurface.

The Indonesian navy plans to eventually lift the wreckage and recover the dead, although the depth poses a significant challenge, Margono said.