Seven children have died after their local water spring was booby trapped with a bomb aimed at Afghan police.
They were grazing farm animals when the device went off in the Taywara district of western Ghor province, said provincial police chief Dilawar Shah.
He said the spring was located in an area that has seen recent fighting between insurgents and police forces, and added that the children accidentally triggered the device as they were grazing cattle.
He said the bomb was intended for security forces that use the same spring as a water supply.
President Hamid Karzai condemned the bombing.
In other violence, the US military said that one of its troops had been killed in western Afghanistan.
The death brings the number of foreign troops killed this month to 36, and the total for this year to 251. Of those, at least 155 have been Americans.