KABUL, Afghanistan — A man dressed in an Afghan border police uniform turned his weapon on American troops in eastern Afghanistan on Monday, killing six soldiers before being killed in a gun battle, NATO's International Security Assistance Force said.
The incident appears to be one of the worst in a string of attacks in which members of Afghan security forces have turned against the international troops with whom they're supposed to be partnered.
All six service members killed were Americans, Pentagon spokesman Marine Col. David Lapan confirmed Monday. He wouldn't name those killed or their unit, pending notification of next of kin.
The incident took place in Nangarhar province, in the remote district of Pachir Agam, Afghan and U.S. officials said. The district, which borders Pakistan, is home to the Tora Bora mountains, where al-Qaida leader Osama bin Laden made a last stand against invading U.S.-led forces in late 2001 before escaping to Pakistan.
U.S.-led troops have been attempting to train Afghan's border police to better control the border, which insurgents and smugglers cross easily.
The killings appear to call into further question the reliability of Afghan forces, which President Obama is counting on to handle security when U.S. combat troops withdraw at the end of 2014.
U.S. officials said it wasn't yet clear whether the assailant was a border police officer or merely dressed in the unit's uniform.
Investigators are "trying to find out who this person was, and why they were there," said a U.S. military official, who wasn't authorized to speak for the record and thus spoke only on the condition of anonymity.
In a brief statement, NATO said the attack took place during a training mission and was under investigation. Other details, including how the assailant was able to kill six soldiers before being fatally shot, weren't divulged.
"The circumstances of the incident are not clear yet," said an Afghan spokesman, Ahmad Zia Abdulzai.
Gen. Aminullah Amarkhil, the commander of Nangarhar border police, said the incident took place around 2:30 p.m.
On Saturday, at least 10 police officers were killed in Paktika province in southeastern Afghanistan when two suicide bombers dressed in police uniforms blew themselves up in the province's police headquarters.
Earlier this month, a soldier from the U.S.-trained Afghan army was reported to have shot two American soldiers in southern Helmand province.