Hundreds of rescue workers are frantically searching for survivors in the rubble. On Wednesday, one survivor and one deceased were found.
Four people have thus been confirmed dead, but since about 90 schoolchildren are still believed to be buried in the rubble, the death toll is feared to rise.
Outside the school, relatives have gathered in hope of a miracle. Cries for help have been heard from within the rubble and rescue workers have tried to send in food, water, and oxygen. But the rescue efforts are hindered by the fact that the building is unstable and is feared to collapse again.
We believe that our children are still alive, says father Abdul Hanan, whose 14-year-old son is missing.
The rescue effort must pick up speed. We are racing against the clock now, he says and bursts into tears.
Dewi Sulistiana is also waiting for news about her 14-year-old son.
I have been here for days. I cry when I think of my son. Why is it taking so long to find him?
The school collapse occurred on Monday afternoon, local time, when about 100 students at the Muslim boarding school on eastern Java gathered for prayer.
About 100 people have been taken to hospital, many of them with head injuries and broken bones. The majority of those affected are boys aged 12-18.
The accident is under investigation, but initial reports point to inadequate construction work when a new floor was recently built on top of the existing ones.
