US Secretary of State Hillary Clinton Friday told a somber ceremony to welcome home four diplomats killed in Libya that their deaths were \"senseless\" and \"unacceptable.\" \"The people of Egypt, Libya, Yemen, and Tunisia did not trade the tyranny of a dictator for the tyranny of a mob,\" Clinton said as the bodies of the four men, including ambassador Chris Stevens, arrived back on American soil. The four remains were carried, one-by-one from a C-17 transport aircraft by seven marines in dress uniform, in transfer cases draped in the US flag into an aircraft hanger at Andrews Air Force base outside Washington. A band played somber music as the cases were lifted into four black hearses parked inside the hanger. \"Today we bring home four Americans who gave their lives for our country and our values,\" Clinton told a gathered audience of family, friends and colleagues of the dead.Amid a fourth day of violent protests targeting US diplomatic missions in the Middle East and North Africa, the top US diplomat also called for calm. \"Reasonable people and responsible leaders in these countries need to do everything they can to restore security and hold accountable those behind these violent acts,\" Clinton said. \"There will be more difficult days ahead, but it is important that we don\'t lose sight of the fundamental fact that America must keep leading the world. We owe it to those four men to continue the long, hard work of diplomacy.\"