Kidnappers in Haiti freed two Swiss relief workers Wednesday after holding them for five days, reports the Associated Press.

The abduction of Doctors Without Borders staff members was the first reported on the island since the catastrophic January 12 earthquake. Some aid groups have imposed dusk-to-dawn curfews amid reports of increasing insecurity in Port-au-Prince.

Charity workers face a growing threat from militant groups, The Seattle Times reports, in the wake of this week’s assault by suspected extremists on the Christian aid group World Vision’s office in northwestern Pakistan, which killed six.

InterAction, the largest coalition of U.S. nonprofit aid groups, said 122 humanitarian workers worldwide were killed in 2008. Some aid groups are evaluating whether to remain in northwest Pakistan following the World Vision attack.