Indonesian rescuers continue to search for missing students after a prayer hall at an Islamic boarding school collapsed, killing at least 50 people.
Using excavators, rescuers late on Sunday cleared 80 per cent of the debris and found the bodies of mostly teenage victims, according to the National Disaster Mitigation Agency.
Rescuers found 35 bodies at the weekend alone and the search will continue for more victims, the agency said.
Budi Irawan, a deputy at the disaster mitigation agency, said 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.
Yudhi Bramantyo, a search and rescue agency official, said the searches indicated the death toll was likely to be at least 54 people.
The structure fell on top of hundreds of students, mostly boys between the ages of 12 and 19, during afternoon prayers on September 30 at the century-old Al Khoziny school in Sidoarjo on the eastern side of Indonesia's Java island.
Only one student escaped unscathed, authorities said, while 97 were treated for various injuries and released. Six others suffered serious injuries and remained hospitalised on Sunday.
Police said two levels were added to the two-storey building without a permit, leading to structural failure. The revelation has triggered widespread anger over illegal construction in Indonesia.
"The construction couldn't support the load while the concrete was pouring (to build) the third floor because it didn't meet standards and the whole 800 square metres construction collapsed," said Mudji Irmawan, a construction expert from Tenth November Institute of Technology.
Rescuers are continuing to search for people among the destruction, which authorities say was caused by a structural construction failure. (Reuters: Dipta Wahyu)
Mr Irmawan also said students shouldn't have been allowed inside a building under construction.
On Friday, rescuers received the parents' permission to make use of heavy equipment after failing to find signs of life during previous efforts.
Rescuers dug through tunnels in the remains of the building, calling out the boys' names and using sensors to detect any movement, but found no signs of life.
Emotional family members of students who were inside the school at the time of the collapsed watched on as rescue efforts unfolded. (Reuters: Dipta Wahyu)
Al Khoziny is an Islamic boarding school known locally as a pesantren.
Sidoarjo district chief, Subandi, confirmed what the police had announced earlier: The school's management had not applied for the required permit before starting construction.
"Many buildings, including traditional boarding school extensions, in non-urban areas were built without a permit," Subandi, who goes by a single name, told news wires agency The Associated Press on Sunday.
Indonesia's 2002 Building Construction code states that permits have to be issued by the relevant authorities prior to any construction, or else face fines and imprisonment. If a violation causes death, this can lead to up to 15 years in prison and a fine of up to 8 billion rupiah ($731,857).
Rescue teams began using excavators and sensors, with the permission of students' families, to detect any signs of life. (Reuters: Stringer)
The school's caretaker is Abdus Salam Mujib, a respected Islamic cleric in East Java. He offered a public apology in a rare appearance a day after the incident.
"This is indeed God's will, so we must all be patient, and may God replace it with goodness, with something much better. We must be confident that God will reward those affected by this incident with great rewards," he said.
Criminal investigations involving Muslim clerics remain sensitive in the world's most populous Muslim-majority nation.
There has been no comment from school officials since the collapse.
"We will investigate this case thoroughly," East Java Police Chief Nanang Avianto said Sunday.
"Our investigation also requires guidance from a team of construction experts to determine whether negligence by the school led to the deaths."
Indonesia, the world's largest Muslim-majority nation, has about 42,000 pesantren serving 7 million students, according to religious affairs ministry data.
AFP/AP/Reuters