SIDOARJO, Indonesia (AP) — Indonesian rescuers are searching on Sunday for missing students after a prayer hall at an Islamic boarding school collapsed almost a week ago. They have recovered 23 bodies over the weekend search, bringing the death toll to 37.

Using jackhammers, circular saws and sometimes their bare hands, rescue teams diligently removed rubble in an attempt to find the 26 missing students.

The structure fell on top of hundreds of students, mostly boys between the ages of 12 and 19, on Sept. 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 95 were treated for various injuries and released. Eight others suffered serious wounds and remained hospitalized Sunday.

Police said two levels were added to the two-story building without a permit, leading to structural failure. This 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 meters (8,600 square feet) construction collapsed," said Mudji Irmawan, a construction expert from Tenth November Institute of Technology.

Irmawan also said students shouldn't have been allowed inside a building under construction.

Sidoarjo district chief, Subandi, confirmed what the police had announced: 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 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 (nearly $500,000).

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."