Updated 7:35 a.m. ET
(CBS/AP) KABUL, Afghanistan Two American soldiers were shot and killed by one of their Afghan colleagues in the east on Monday, military officials said, bringing to 12 the number of international troops all Americans to die at the hands of their local allies this month.
Details were sketchy, but local sources have told CBS News that the U.S. and Afghan troops were on a joint patrol in a fairly remote area of Laghman province when some kind of dispute broke out after they set up a checkpoint. Those details could not be confirmed and an official investigation is still ongoing.
But Afghan officials painted a different picture, saying the attack appeared to have been an accidental shooting.
When a group of U.S. and Afghan soldiers came under attack, they returned fire and ran to take up fighting positions, said Noman Hatefi, a spokesman for the Afghan army corps in eastern Afghanistan. But an Afghan soldier fell and accidentally discharged his weapon, killing two American soldiers with the errant rounds, he said.
"He didn't do this intentionally. But then the commander of the unit started shouting at him, 'What did you do? You killed two NATO soldiers!' And so he threw down his weapon and started to run," Hatefi added.
The U.S. troops had already called in air support to help with the insurgent attack and the aircraft fired on the escaping Afghan soldier from above, killing him, Hatefi said.
NATO spokesman Lt. Col. Hagen Messer of Germany confirmed that two international soldiers were killed by an Afghan soldier in Laghman province, but declined to give further comment.
Insider attacks have been a problem for the U.S.-led military coalition for years, but it has exploded recently into a crisis. There have been at least 32 attacks so far this year, killing 42 coalition members, mostly Americans. Last year, there were 21 attacks, killing 35; and in 2010 there were 11 attacks with 20 deaths.
Meanwhile, Helmand officials reported that 10 Afghan soldiers were killed in an attack on a checkpoint in the south, and five were either kidnapped or joined their assailants.
Helmand provincial government spokesman Daoud Ahmadi said insurgents attacked the checkpoint in Washir district Sunday evening. Another four soldiers were wounded, he said.
Ahmadi did not provide details of the attack. He said the five missing soldiers left with the insurgents, but it was unclear if they were kidnapped or went voluntarily.