Officials in Afghanistan say unknown assailants have shot and killed five aid workers, including three foreigners.
Afghan officials say the aid workers were killed in an ambush Wednesday.
The victims, two of whom were Afghan and three of whom were foreign, had been working for Medecins Sans Frontieres (Doctors Without Borders) in the northwest province of Badghis.
Some reports attribute the killings to militant remnants of Afghanistan's former Taleban government.
The Taleban have been waging an armed insurgency against Afghan government targets, as well as foreign aid groups and the U.S. military, since their overthrow by a U.S.-led coalition in 2001.
Most of the insurgent activity has so far been confined to the east and south of the country. Wednesday's killings, however, took place in the remote northwest, near the border with Turkmenistan.
On Tuesday, the top U.S. military commander in Afghanistan, Lieutenant General David Barno, told reporters Taleban attacks would likely intensify.
He said the Taleban and its allies, including the al-Qaida network, hope to increase insecurity in the country in an attempt to undo plans for Afghanistan's first post-Taleban elections.
"As the September elections approach, we can expect to see additional attempts by remnants of the Taleban and al-Qaida to disrupt and undermine Afghanistan's democratic process," he said.
The national elections were originally planned for this month, but were postponed until September, in part because of security problems hampering voter registration.