Four U.S. soldiers in Afghanistan were shot dead and two wounded on September 16 by at least one Afghan police officer -- the second such attack against NATO-led troops within 24 hours.
The bodies of the four dead soldiers from the International Security Assistance Force were found in the southern province of Zabul by a team of NATO reinforcements that arrived from another checkpoint nearby.
One of six officers from the Afghan National Police (ANP) who were operating the security post with the slain ISAF soldiers also was found dead.
The whereabouts of the other five Afghan police are not immediately known.
ISAF spokesman Brigadier General Guenter Katz confirmed to RFE/RL's Radio Free Afghanistan that the ISAF troops were killed by one or more members of the Afghan National Police.
"Four ISAF service members have been killed by members of the Afghan police," Katz said. "This incident is still under investigation. And as soon as we have more findings, we'll inform you about that."
The incident takes to six the number of foreign soldiers killed this weekend in so-called "insider attacks."
On September 15, a local Afghan police officer killed two British soldiers in Helmand Province in restive southern Afghanistan.
Katz confirmed the police officer was shot dead by coalition forces during a gun battle that followed.
"We had an insider attack where a member of the Afghan local police [killed] two British soldiers, wounding another British soldier," Katz said. "The shooter [was] killed during that incident."
At least 51 foreign military personnel have been killed as a result of insider attacks -- also known as "green-on-blue" attacks -- in Afghanistan this year.
In an attempt to clamp down on such attacks, the Afghan Defense Ministry last week began distributing guidebooks on foreign culture
to Afghan security personnel.
NATO says about one-quarter of the insider attacks are thought to be carried out by militants or Taliban fighters who have infiltrated Afghanistan's security forces.
It says the majority of insider attacks are the result of misunderstandings, cultural differences, and Afghan soldiers harboring personal grudges against some of those who are training the 350,000-strong Afghan National Army and the Afghan National Police.
With reporting by Reuters and AP