PARACHINAR, Pakistan -- A Pakistani police officer says a hand grenade has killed six children who found it while playing in a field in a northwestern town.

Mian Iftikhar, police chief of Hangu where the incident took place Sunday, says the dead girl and five boys belong to two families displaced from a nearby tribal region, Orakzai.

The region lies near restive areas on the Afghan border that are home to Pakistani and al-Qaida-linked foreign Islamic militants. The military has carried out offensives in the area.

The violence has displaced many civilians, who seek shelter in refugee camps or with relatives. Last week, thousands fled one tribal area, North Waziristan, after the Pakistani air force carried out strikes there.