The girl was tricked by the Taliban to carry a bag containing a bomb that was set off remotely as the girl neared a police vehicle Sunday in the remote village of Uwshi in central Char Chino district, police told The New York Times.
Police said only the girl died in the explosion. Police official Fazal Ahmad Shirzad said he believed the girl was not aware the bag she was carrying contained a bomb.
Separately, the death toll from the bombing Saturday at a small hospital in southeastern Logar province rose to 37, the provincial health director said. Another 53 were wounded in the attack.
The health director warned the actual number of those killed was likely higher as many of the victims' relatives took the bodies to their own villages.
Separately, four NATO soldiers died in other parts of the country, the report said.
Two of them were Spanish soldiers killed by an improvised explosive device blast in western Afghanistan. The other two died in separate incidents in southern and eastern Afghanistan, but NATO had not yet disclosed their nationalities.