A rogue Afghan Air Force pilot opened fire on NATO troops at Kabul Airport, killing eight American service members and one American contractor on Wednesday. The pilot, Gul Ahmad, was also killed in the shootout. The reasons are still unclear, though. An Afghan official said Ahmad suffered from “mental illness,” but there were also reports that the gunfight followed an argument between the pilot and the foreign troops. Meanwhile, the Taliban has claimed responsibility for the attack, saying the gunman was impersonating an officer. Authorities, however, have not confirmed a connection to the Taliban.