A spokesman for the International Committee of the Red Cross in Afghanistan says five members of their Afghan staff members have been abducted, the Associated Press reported.
Marek Resich said Saturday that the employees were traveling by road in the western province of Herat on Friday when they were detained by a local armed group.
He said the organization is trying to secure their release.
Raouf Ahmadi, a police spokesman in Herat, said the aid workers were delivering sheep to local villages when they were stopped by the gunmen.
Militants carry out near-daily attacks in Afghanistan, usually targeting security forces.
But recent attacks have rattled civilian aid workers. On July 24, gunmen opened fire on two Finnish aid workers in the city of Herat, killing them both.