The death toll from the school collapsed in Indonesia last week on 29 September has climbed to at least 50 people as rescuers have cleared nearly all of the debris, rescue authorities said on Monday, in the country's deadliest disaster this year.

Piles of concrete caved in on hundreds of mostly teenage boys at the Al Khoziny Islamic boarding school in the Indonesian town of Sidoarjo, in East Java province, trapping and killing them.

Late on Sunday, rescuers said they cleared 80% of the debris using excavators and found bodies and body parts of mostly teenage victims, the disaster mitigation agency said in a statement.

Budi Irawan, a deputy at the disaster mitigation agency, said a total of 50 people have died based on the bodies recovered and rescuers were expected to finish their search by the end of Monday for 13 more trapped victims.

"The number of victims is the biggest this year from one building," he told a press conference.

"Out of all the disasters in 2025, natural or not, there hasn't been as many dead victims as the ones in Sidoarjo," Irawan said.

Yudhi Bramantyo, a search and rescue agency official, said at the same news conference that five other body parts were found, indicating the death toll is likely to be at least 54 people.

Rescuers are continuing their search, with footage shared by the search and rescue agency showing recovery workers carrying orange body bags out of the ruins of the school.

Authorities have said the cause of the collapse was construction work on the upper floors that the school's foundations could not support.

Across Indonesia, there are about 42,000 Islamic school buildings, known locally as a pesantren, data from the country's religious affairs ministry shows.

Only 50 pesantren (boarding schools) have building permits, Dody Hanggodo, the country's Public Works Minister, was quoted by local media as saying on Sunday.

It is not immediately clear if Al Khoziny had a building permit.

Reuters could not immediately contact school authorities for comment.

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