U.S. and Afghan forces came under attack in eastern Afghanistan on Saturday, officials said in Kabul as they launched investigations into whether the attackers were Afghan service members or wearing Afghan uniforms, what is known as an "insider attack."
Colonel Sonny Leggett, a spokesman for U.S. forces in Afghanistan, said a combined U.S. and Afghan force conducting an operation in Nangarhar province was engaged by direct fire.
Officials did not comment on the number of casualties.
"We are assessing the situation and will provide further updates as they become available," he said.