KABUL, Afghanistan — A joint U.S.-Afghan raid Thursday against the Taliban involving NATO airstrikes left 26 civilians and three Afghan troops dead in Kunduz province, Afghan officials said.

Two U.S. soldiers were killed in a separate ground clash there as investigators worked to determine what went wrong.

The Americans killed and four other U.S. troops wounded were among military advisers helping Afghan troops, rare combat casualties for Western forces who handed over the task of securing Afghanistan to local troops about two years ago.