There are no signs of life under the wreckage of a collapsed Indonesian school where 59 people are still missing, rescuers have said.

Hundreds of students, most of them teenage boys, were inside the two-storey Islamic boarding school in the town of Sidoarjo when it collapsed on Monday. At least five students were killed and about 100 injured, officials said.

Thirteen people have been freed from the debris since rescue efforts began, though two later died in hospital. Rescue operations had been challenging due to the unstable structure of the building.

On Thursday, the disaster mitigation agency (BNBP) reported that rescuers using thermal drones failed to detect signs of life from the rubble.

Last night, we even [cleared] the area to ensure silence. [We] hoped that with the use of sophisticated equipment... we might hear some signs of life, Lt Gen Suharyanto, the head of the BNBP, stated at a press conference on Thursday afternoon. Scientifically, no signs of life were found.\p>

Rescuers had not been able to use heavy equipment earlier due to fears it could lead the building to collapse further, risking the lives of any possible survivors. However, they are now moving to the next phase of operations - using heavy equipment to lift or cut concrete slabs.

Families are anxious as they wait for news, holding onto hope despite the dire situation. Maulana Bayu Rizky Pratama, whose 17-year-old brother is among the missing, expressed his sorrow, saying, I feel sad thinking of him being down there for four days..

The BNBP indicated that the building was under construction and lacked the necessary permits to add the additional floors, which contributed to its instability.