BENGHAZI, Libya — The head of the Transitional National Council said Saturday that Libyan fighters had surrounded key loyalist-controlled cities where many believe Moammar Gaddafi and three of his sons could be holed up, waiting for a showdown. The council has extended until Sept. 10 a deadline for Sirte, Bani Walid, Jufra and the desert city of Sabha to surrender or face a military onslaught.