Rescuers clawed through unstable slabs of concrete and twisted steel in East Java on Tuesday, racing to free dozens of students still believed trapped beneath a collapsed Islamic boarding school, as anguished families looked on, some praying, others sobbing in despair.

The disaster struck Monday afternoon at Al Khoziny Islamic Boarding School in Sidoarjo, about 480 miles east of Jakarta, where students had gathered for prayers inside a four-story hall.

Without warning, the upper levels gave way, crushing worshippers below.

By Tuesday evening, officials confirmed at least three dead and more than 100 injured, many of them boys between ages 12 and 18. Rescuers said 38 people were still unaccounted for.

Frantic rescue efforts