Five American troops were killed in an apparent friendly fire airstrike in Afghanistan, the Pentagon confirmed Tuesday, marking one of the deadliest such incidents of the nearly 13-year-old war.
"Five American troops were killed yesterday during a security operation in southern Afghanistan," Pentagon press secretary Rear Adm. John Kirby said in a statement. "Investigators are looking into the likelihood that friendly fire was the cause. Our thoughts and prayers are with the families of these fallen."
The troops were special operation forces, according to a coalition official. He asked that his name be withheld because he is not authorized to speak about the incident, which occurred in Zabul province in southern Afghanistan, a violent area that borders Pakistan's tribal areas.
The Associated Press and Afghanistan's Pajhwok Afghan News reported that Monday's event took place in Arghandab district of Zabul when troops called for air support during an operation.
A statement issued from coalition headquarters in Kabul did not include the nationalities of the casualties, but said the incident is under investigation.
"Tragically, there is the possibility that fratricide may have been involved," the coalition statement said.
In March, a NATO airstrike in Afghanistan's eastern Logar province killed five Afghan soldiers and wounded 8 others.
The incident comes as U.S. and allied forces are drawing down and turning the fight over to Afghan security forces.
The most well-known and controversial friendly fire death took place in 2004, when Army Ranger and former professional football player Pat Tillman and an Afghan national were killed in a battle near the Pakistan border. The Pentagon initially announced that Tillman was killed by enemy fire, but a month later revealed that another group of coalition forces had mistaken Tillman's group for the enemy.
In this week's incident, provincial Police Chief Gen. Ghulam Sakhi Rooghlawanay told the Associated Press that after a joint operation by Afghan and NATO, "the joint forces came under the attack of insurgents, and then foreign forces called for air support."
"Unfortunately five NATO soldiers and one Afghan army officer were killed mistakenly by NATO airstrike," he said.
Pajhwok reported that an interpreter also was killed. Taliban spokesman Qari Yusuf Ahmadi told Pajhwok that Taliban fighters were locked in a gun battle with foreign troops when coalition planes bombed their own troops.
The deaths bring to 36 the number of NATO troops killed so far this year in Afghanistan, including eight in June.
About 50,000 coalition troops are stationed in Afghanistan, more than 32,000 of them Americans. The U.S. force is scheduled to be trimmed to less than 10,000 next year.
Contributing: John Bacon