Six children playing in a field in rural Pakistan were killed Sunday when a hand grenade they mistook for a toy exploded, police said.

Hangu district police officer Ifitkhar Ahmed said the two girls and four boys were between ages seven and 12.

Another child was injured.

The incident occurred in Babar Mela, about 3 miles (5 kilometers) southwest of Hangu, a troubled district bordering Pakistan's tribal areas. Hangu is rife with sectarian violence between Shia and Sunni Muslims.

Earlier this month, a 14-year-old boy tackled a suicide bomber and died at the main gate of his school in Hangu, saving schoolmates gathered for their morning assembly. Two other people were injured when the bomber set off his device.