KABUL, Afghanistan — A United States military investigation into claims of civilian casualties during a joint operation by Afghan and American forces found that 33 civilians were killed and 27 others were wounded during a firefight and airstrikes in Kunduz Province last year, American military officials said on Thursday.

In early November, Afghan Special Forces, accompanied by American military advisers, came under intense fire during an operation to arrest Taliban commanders in Boz Qandahari, a village in Kunduz, the United States military command in Afghanistan said in a statement. They called in American airstrikes, which resulted in some of the civilian casualties.

Two American soldiers and three Afghan commandos were killed, and four American soldiers and 11 commandos were wounded, the statement said.

“Regardless of the circumstances, I deeply regret the loss of innocent lives,” said Gen. John W. Nicholson Jr., the commander of United States forces in Afghanistan. “On this occasion, the Taliban chose to hide amongst civilians and then attacked Afghan and U.S. forces.”