Story highlights An 8-year-old and a 10-year-old are among those killed by militants, police say

The attack targeted the family of a pro-government militia chief who was killed last week

The militants took all the male family members outside and killed them, police say

Militants in northwestern Pakistan have killed nine family members of a slain leader of a pro-government militia, including at least two children, police said Wednesday.

About 20 to 25 militants attacked the family's house on the outskirts of the city of Peshawar early Wednesday, said Najeeb ur Rehman, a senior police official.

The attackers took the male members of the family outside and locked the female members inside, said Rahim Shah, another senior police official. They then proceeded to killed all the male family members, including two boys aged 8 and 10, he said.

Those killed were relatives of Zafar Khan, the chief of a local peace committee and member of a special police force, who was killed last week in a clash with militants. The skirmish last week left one militant dead.

Local peace committees are volunteer pro-government militias that fight to drive militants out of their areas.

The militants who attacked the family's house have not been captured, Rehman said, and there has been no claim of responsibility for the attack.