Three American soldiers were shot and killed on Friday in Afghanistan by a man in an Afghan army uniform, the Associated Press reports.
The attacker, a member of the police in Helmand province, joined the insurgency after the attack, the Taliban confirmed to AP. This is the third such attack on coalition forces this week.
U.S. officials have previously touted the importance of local police in fighting the insurgency and stabilizing Afghanistan in the years to come. The U.S. and other international troops are set to withdraw by 2014.
On Tuesday, an American soldier was killed when two gunmen wearing Afghan uniforms opened fire in the eastern Paktia province. Two others were injured. And on Thursday, two men wearing Afghan uniforms shot at a group of NATO forces. No coalition troops were killed in the attack.
In total this year, according to the AP, 30 coalition troops have been killed in 20 such attacks.
Earlier this week, four other Americans were killed by two suicide bombers in eastern Afghanistan.