3 U.S. service members dead in second "green-on-blue" attack

(CBS/AP) KABUL, Afghanistan - An Afghan working on an installation shared by Afghan and foreign forces shot and killed three American service members Friday - raising to six the number of U.S. troops killed by their Afghan partners in 24 hours.

In an earlier attack, an Afghan police officer shot and killed three U.S. Marines after sharing a meal with them before dawn Friday in Sangin district of Helmand province. 

Coalition spokeswoman Maj. Lori Hodge said Saturday that the three additional foreign service members were gunned down Friday night. The second incident occurred in Garmser district of Helmland province, according to province spokesman Daud Ahmadi

The Taliban claimed responsibility for both of the attacks in Helmand province, located in southern Afghanistan. The province is an area where Taliban insurgents have wielded their greatest influence.

Hodge says the shooters in both attacks have been detained.

The most recent shooting brings the number of "green-on-blue" incidents - in which Afghan security forces turn on their Western allies - to 26 over the last 12 months. Thirty-four coalition service members have now died this year at the hands of Afghan forces or insurgents disguised in Afghan uniforms, according to NATO - a dramatic rise from previous years.

Gen. John Allen, the commander in Afghanistan, said insider attacks are rare compared to the overall number of troops in what's officially called the International Security Assistance Force - ISAF for short.

"Every case where one of these occurs," said Allen, "that same day there are tens of thousands of interactions between the Afghans and ISAF forces that don't go that way."

While the Taliban often claim they have infiltrated the Afghan security forces and are carrying out these attacks, CBS News reporter John Bentley reported in July that a U.S. Defense Department report maintains the attacks are not carried out by insurgents.

"Investigations have determined that a large majority of green-on-blue attacks are not attributable to insurgent infiltration of the ANSF (Afghan National Security Forces), but are due to isolated personal grievances against coalition personnel," the report said.