Six children were killed when a grenade exploded on Sunday and one injured in Babar Mela area of Hangu district in Khyber Pakhtunkhwa.
News reports quoting the police said that the grenade was found in a field by the children, all said to be from one family, and it exploded while they were playing with it. Five boys and one girl died in the explosion while one boy is in hospital.
The house near where the explosion took place is being searched.
The region lies near restive areas on the Afghan border that are home to Pakistani and al-Qaeda-linked foreign Islamic militants. The military has carried out offensives recently in the tribal areas. The violence has displaced many civilians, who sought shelter in refugee camps or with relatives. Last week, thousands fled one tribal area, North Waziristan, after the Pakistani air force carried out airstrikes.