RESCUE workers ran oxygen and water to students trapped in the unstable concrete rubble of a collapsed school building in Indonesia, as they desperately worked to free survivors yesterday a day after the structure fell.

At least three students were killed, more than 100 were injured and dozens were presumed buried in the rubble.

Rescue workers, police and soldiers digging through the night pulled out eight weak and injured survivors more than eight hours after the collapse at Al-Khoziny Islamic Boarding School in the East Java town of Sidoarjo.

Rescuers saw additional bodies, indicating the death toll was likely to rise.

The students are mostly boys between ages 12 and 18.

Families anxiously awaited news at hospitals or near the collapsed building. A notice posted at the school complex Tuesday morning listed 65 students as missing.

“Oh, my God my son is still buried, oh my God please help,” a mother cried after seeing her child’s name on the board, followed by the cries of other parents whose relatives had suffered a similar fate.

Heavy slabs of concrete and other rubble and unstable parts of the building hampered search and rescue efforts, said Nanang Sigit, a search and rescue officer leading the effort.

“We have been running oxygen and water to those still trapped under the debris and keeping them alive while we work hard to get them out,” Mr Sigit said.

He added that rescuers saw several bodies under the rubble but were focused on saving those who were still alive.

Several hundred rescuers were involved in the effort and had equipment for breathing, extrication, medical evacuation and other support tools.

The students had been performing afternoon prayers in a building that was undergoing an unauthorised expansion when it suddenly collapsed on top of them, provincial police spokesperson Jules Abraham Abast said.

Authorities have opened an investigation into the cause of the building collapse.