Indonesian rescuers were racing on Tuesday to find 38 people feared trapped beneath the rubble of an Islamic boarding school that collapsed in East Java during afternoon prayers, killing three, according to disaster officials.

Axar.az informs, citing Reuters, three people were confirmed dead and 99 others survived Monday's collapse at the Al Khoziny boarding school in Sidoarjo, a town about 780 km east of Jakarta, according to Mohammad Syafii, head of Indonesia's search and rescue agency.

Earlier on Tuesday, disaster mitigation agency spokesperson Abdul Muhari said the unstable building collapsed during construction. "This sudden occurrence caused building material to fall on dozens of students and workers," he said.

The disaster mitigation agency said the building's foundations allegedly could not support the weight of construction on its fourth floor.