ISLAMABAD (AP) - Suspected militants armed with grenades attacked the offices of an international aid group in northwest Pakistan on Wednesday, killing five people working for the organization, police said.

The attack targeted World Vision, a large Christian humanitarian group helping survivors of the 2005 Kashmir earthquake in Mansehra district.

The dead were all Pakistanis and included two women, said police official Mohammad Sabir.

Al-Qaida, the Taliban and allied groups are strong in northwestern Pakistan, but Mansehra lies outside the tribal belt next to Afghanistan where the militants have their main bases.

Extremists have killed other people working for foreign aid groups in Pakistan and issued statements saying such organizations were working against Islam, greatly hampering efforts to raise living standards in the desperately poor region.

The aid groups are seen by the militants as a challenge to their authority in regions under their influence.

They often employ women and support female rights initiatives, further angering the extremists.

Many foreign aid groups set up offices in Mansehra after the 2005 earthquake, which killed about 80,000 people.

In 2008, militants in Mansehra killed four Pakistanis working for Plan International, a British-based charity that focuses on helping children.