Mostly students and civilians were among 16 people killed and 24 others wounded in a blast that hit a madrassa in Afghanistan's northern city of Aybak on Wednesday.
There have been dozens of blasts and attacks targeting civilians since the Taliban returned to power in August last year, most claimed by the local chapter of Daesh.
A doctor in Aybak, about 200 kilometers (130 miles) north of the capital Kabul, said the casualties were mostly youngsters.
"All of them are children and ordinary people," he told AFP, asking not to be named.
A provincial official confirmed the blast, but could not provide casualty figures.
A provincial official confirmed the blast at an Islamic religious school, but could not provide casualty figures.
The Taliban, which frequently plays down casualty figures, said 10 students had died and "many others" were injured.
"Our detective and security forces are working quickly to identify the perpetrators of this unforgivable crime and punish them for their actions," tweeted Interior Ministry spokesman, Abdul Nafay Takor.
Images and videos circulating on social media – which could not immediately be verified – showed Taliban fighters picking their way through bodies strewn across the floor of a building.
Prayer mats, shattered glass and other debris littered the scene.
Aybak is a small but ancient provincial capital that came to prominence as a caravan-stopping post for traders during the fourth and fifth centuries when it was also an important Buddhist center.
There has been a lull of a few weeks between major blasts targeting civilians in Afghanistan, although several Taliban fighters have been killed in isolated attacks.
In September, at least 54 people – including 51 girls and young women – were killed when a suicide bomber detonated a device at a hall in Kabul packed with hundreds of students sitting for a practice test for university admissions.
No group claimed responsibility for that bombing, but the Taliban later blamed Daesh and said it had killed several ringleaders.
In May last year, before the Taliban's return to power, at least 85 people – mainly girls – were killed and about 300 were wounded when three bombs exploded near their school in the neighborhood.
No group claimed responsibility, but a year earlier Daesh claimed a suicide attack on an educational center in the area that killed 24.
The Taliban's return to power brought an end to their insurgency, but Daesh continues to stage attacks across the country.
The Taliban movement – made up primarily of ethnic Pashtuns – has pledged to protect minorities and clamp down on security threats.
