The Defense Department says it is looking into the circumstances surrounding the deaths of two U.S. service members killed in a raid on ISIS leaders in eastern Afghanistan this week.According to a statement released by the headquarters of United States Forces—Afghanistan, "USFOR-A is investigating the possibility that the two Rangers were accidentally killed by friendly fire during the more than three-hour fight. We have informed both of their families of this possibility and we have appointed a team to investigate the Soldiers' deaths."Preliminary details of the raid against ISIS-Khorasan were reported in the Two-Way yesterday.The statement added, "We investigate all combat deaths of U.S. service members, and because we believe that there is a possibility of friendly fire in this case, it is appropriate to notify the families. Once the investigation is complete, USFOR-A will provide the results to our chain of command."The slain soldiers were identified in a subsequent statement issued by Defense Secretary Jim Mattis.