At least two schools in north-west Pakistan are known to have been destroyed by the powerful earthquake, killing at least 400 children.
Witnesses have spoken of seeing dozens of other schools flattened in villages across the mountainous region.
Schoolchildren would have been settling down to morning lessons when the quake hit at 0850 (0350GMT) on Saturday.
At least 18,000 people died in the 7.6-magnitude quake that hit Pakistan, India and Afghanistan.
The bodies of 400 children have been pulled from the rubble of at least two schools alone in Pakistan's North West Frontier Province.
Police chief Riffat Pashar told Reuters news agency 350 altogether had died in the collapse of one school in Mansehra district.
"Fifty were killed in another school in the same district," he said.
Schools in the area around Balakot town have reported to have been particularly badly hit.
An AFP correspondent said all the schools in the surrounding villages had been either completely destroyed or very seriously damaged.
"We had three schools here, a primary school, a middle school and a girls' school. They're all gone," soldier Mohammed Iqbal of Patangi village, some 7km (four miles) from Balakot, told the AFP news agency.
"Out of 190 children we were able to pull out only 40 alive. The rest are trapped and probably dead."
Abdul Rashid, a government official in another nearby village, Shawal, told AFP: "Many children from our village went to Balakot and only one of them has come back.
"We tried to look for them yesterday but there was no way we could get there because of the landslides. We couldn't go on foot because of the falling boulders and aftershocks".