KABUL: An Afghan police official says that an explosion has struck a group of children who were playing on the outskirts of a provincial capital in the country's north, killing three boys and wounding 12 children, four of them critically.

Provincial police spokesman Jawed Basharat says the explosion took place on Tuesday at the outskirts of Puli Khumri, the capital of Baghlan province. He says the victims were all between 7 and 12 years old.

Basharat says it wasn't immediately clear what the source of the explosion was and that it could have been a land mine or some other left-over ordnance from the wars.

Afghanistan still regularly sees explosions from left-over land mines and other unexploded ordnance that kill dozens of people despite decades of clean-up efforts across the country.