More than 10 ambulances lined up near a collapsed Islamic school building in Indonesia's East Java province on Friday as rescuers continued their search for nearly 60 students still trapped under the rubble, a Reuters witness said.

The Al Khoziny school in the town of Sidoarjo collapsed on Monday, cratering upon hundreds of teenage students during afternoon prayer, its foundations unable to support ongoing construction work on its upper floors.

The trapped students were mostly teenage boys between the ages of 13 to 19. Alongside the ambulances was a crane deployed to excavate some of the debris.

By late Thursday, five had been confirmed dead and 30 people were in treatment in the hospital, Indonesia's disaster officials said.

Rescuers found no signs of life on Thursday after digging through tunnels in the remains of the building, despite calling out the boys' names and using sensors to detect any movement.

Al Khoziny is an Islamic boarding school known locally as a pesantren.

Indonesia, the world's largest Muslim-majority nation, has a total of about 42,000 pesantren, serving 7 million students, according to data from the country's religious affairs ministry.