Indonesian rescue workers began using heavy equipment to remove rubble from a collapsed Islamic boarding school after advanced detection devices no longer picked up signs of life.

The country’s disaster agency said on Thursday.

The decision marked a shift from painstaking manual searches that had been carried out since the four-storey prayer hall of the Al Khoziny boarding school in East Java’s Sidoarjo district caved.

The incident happened during afternoon prayers on Monday.

Rescue workers on Wednesday pulled five people alive, but nearly 60 others, mostly aged between 13 and 18, remained unaccounted for, the National Disaster Management Agency said.

Two bodies that were recovered on Wednesday brought the confirmed death toll to five.

Rescuers had deployed thermal drones and other sensors to detect life beneath tonnes of concrete, bricks, and twisted iron rods, agency chief Mr Suharyanto said.

“We sterilised the site and made it completely quiet so that if there were any signs of life, our equipment could pick it up. But there were none,” Mr Suharyanto told reporters.

Excavators and other heavy machinery are being used to clear the collapsed concrete and iron beams, he said.

Authorities stressed that the work would proceed cautiously to avoid further danger to trapped victims.

To prevent further collapse, teams had avoided cranes and heavy machinery, instead crawling through shafts less than 60 centimetres wide and working manually with hand tools.

More than 200 personnel are participating in the operation, including troops, police officers, engineering experts, and civil engineering specialists experienced in building collapses, Mr Suharyanto said.

The multi-storey school caved in during concrete-pouring work when a supporting column reportedly gave way.

Around 100 people survived the collapse, with many still receiving treatment in the hospital.

Indonesia, the world’s largest Muslim-majority nation with about 240 million adherents, is home to tens of thousands of traditional Islamic boarding schools, known as pesantren.

Monday’s disaster has renewed concerns over building standards, which are often poorly enforced nationwide.

(dpa/NAN)