File photo: afghan policemen keep watch at the site of a blast in Kabul, Afghanistan
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 the Islamic State group.
A doctor in Aybak, about 200 kilometres (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.