Two more U.S. troops killed by Afghan gunmen

It was not immediately clear how many shooters were involved. Mr. Sarhadi said a civilian literacy instructor who had taught Afghan soldiers seized a gun from an Afghan army soldier and opened fire. Other American soldiers returned fire, killing both the instructor and the soldier.

NATO, however, said it believed there were two attackers.

“Two individuals, one believed to be an Afghan National Army service member and the other in civilian clothing, turned their weapons indiscriminately against International Security Assistance Force and Afghan National Security Force service members in southern Afghanistan today, killing two ISAF service members,” NATO said in a statement.