World Vision’s office in northwestern Pakistan was attacked Wednesday by militants armed with grenades, killing 6 workers.

The gunmen entered the office near the town of Mansehra, threw grenades, opened fire on the staff and placed a homemade bomb in the office before leaving. Besides those killed, eight employees were hospitalized with injuries.

World Vision, a Seattle-based Christian aid organization, had been in Pakistan since 1992, helping with relief and development work in the country. It began operations in the Mansehra district after a massive earthquake hit the area in 2005. The staff was made up of local citizens, and the local leaders have strongly condemned the attack, according to a statement by World Vision.

Other foreign aid groups in Pakistan have been attacked by extremists groups out of a fear that the organizations are working against Islam and challenging their authority. Pakistan is the second most populous Muslim-majority country with 96 percent of the country following Islam. Christians make up only 1.6 percent of the population.

World Vision has currently suspended all operations across Pakistan indefinitely.