Three Marines were killed instantly, and the fourth was seriously wounded but the gunman escaped. NBC's Jim Miklaszewski reports.
Updated at 12:35 p.m. ET: KABUL, Afghanistan -- A man wearing an Afghan army uniform shot and killed three American Marines, the U.S. military command said Friday. Afghan officials said the victims were American special operations forces troops.
Reuters reported that an Afghan police commander opened fire on the service members after inviting them to a meeting to discuss security. A U.S. military official confirmed the three deaths and said another service member had been injured during the incident.
NBC News' Jim Miklaszewski reported that a "lone gunman" remained on the loose and was being hunted. U.S. military officials said all of the American victims were Marines.
Citing Afghan officials, Reuters said the American special operations forces members were killed late Thursday while attending a meeting in the Sarwan Qala area, in what appeared to be a planned attack by rogue Afghan forces.
"The commander was Afghan National Police in charge of local police in Sangin," a senior Afghan official told Reuters on condition of anonymity. Sangin is a district of Helmand province.
"It looks like he had drawn up a plan to kill them previously," the official added.
A military official told NBC News' Courtney Kube that it was unclear whether the gunman was a member of the Afghan security forces or whether he was just wearing a uniform.
Taliban spokesman Qari Yousef Ahmadi told The Associated Press by telephone that the attacker, whom he identified as a member of Helmand police named Asadullah, had been helping U.S. forces train Afghan local police troops. However, the Taliban has made false claims about the details of attacks in the past.
A U.S. military official says three American service members were killed and one was wounded after a gunman opened fire on them. NBCNews.com's Dara Brown reports.
The attack is the third killing this week of coalition soldiers by Afghans who are training to take over responsibility for security once most international forces leave in 2014.
So-called "green on blue" shootings, in which Afghan police or soldiers turn their guns on their Western mentors, have seriously eroded trust between the allies.
According to NATO, there have been 24 such attacks on foreign troops since January in which 28 people have been killed. Last year, there were 21 attacks in which 35 people were killed.
Senior Army leader slain
Earlier, the Pentagon confirmed that three U.S. service members -- including a senior Army leader -- and an American aid worker were killed Wednesday by a suicide bomber in Kunar province.
The victims included Command Sgt. Maj. Kevin J. Griffin, the most senior enlisted soldier for the 4th Brigade Combat Team, 4th Infantry Division. Griffin, 45, of Riverton, Wyo., was a Bronze Star recipient who first enlisted in the Army in 1988.
Maj. Thomas E. Kennedy, 35, of West Point, N.Y., and Air Force Maj. Walter D. Gray, 38, of Conyers, Ga., were also killed. USAID foreign service officer Ragaei Abdelfattah was identified as the other victim.
On Tuesday, two gunmen wearing Afghan army uniforms killed a U.S. soldier and wounded two others in Paktia province in the east.
And on Thursday, two Afghan soldiers tried to gun down a group of NATO troops outside a military base in eastern Afghanistan. No international forces were killed, but one of the attackers was killed as NATO forces shot back.
NBC News' Courtney Kube, Jim Miklaszewski and Atia Abawi, The Associated Press and Reuters contributed to this report.
Ahmad Jamshid / AP
More than ten years after the beginning of the war, Afghanistan faces external pressure to reform as well as ongoing internal conflicts.
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