KABUL, Afghanistan — U.S. and Afghan forces came under fire on Thursday while targeting senior Taliban commanders during a joint operation in northern Kunduz province, calling in airstrikes during an assault that killed 26 civilians, three local troops and two American service members, NATO and local officials said.

NATO described the Americans killed and two other Americans wounded as being part of “a train, advise and assist mission,” rare combat casualties for Western forces who handed over the task of securing Afghanistan to local troops some two years ago.

Meanwhile, Afghan officials said they were still investigating the attack and its civilian casualties, some of which may have been caused by the airstrikes. Residents later carried over a dozen corpses of the dead, including children, toward the local governor’s office in a show of rage a year after American forces attacked an area hospital.

NATO declined to identify the Americans killed, pending notification of their next of kin. NATO and the Pentagon did not respond to a request for comment from The Associated Press to further clarify the American troops’ mission in the area.