BANJARMASIN (Indonesia)  — Indonesian authorities were preparing on Friday to right a capsized passenger ferry that went down in the Java Sea last week, a navy official said, with dozens of people still missing.

The Virgo Transport 8 carried 213 passengers and 30 crew when it lost contact with its shipping company after departing from Indonesia’s second city of Surabaya on Java island on Sunday, headed for Banjarmasin on Borneo island.

At least six people have died and 129 are missing, according to the national search and rescue agency, Basarnas. Some of the victims are feared trapped inside the vessel, which is now submerged.

An expert team has been brought in to assist the operation to right the ferry, local navy commander Galih Nurna Putra told reporters on Friday.

“The salvage operation is underway,” Galih said, adding that “there was an observation yesterday”.

The head of the Banjarmasin search and rescue agency, I Putu Sudayana, said teams would be able to resume the recovery of bodies once the vessel is righted.

Before that process is completed, divers face risks if they try to enter the capsized ship, he said.