Central Intelligence Agency (CIA) officers stationed at the US Embassy in Iran suddenly found themselves as hostages. They, along with other embassy employees, were held by radical Islamist students in the American Embassy for 444 days. The CIA has posted (on their website) the story of their days in captivity. See "444 Days in Tehran: The Story of CIA Officers Held Captive During the Iranian Hostage Crisis", Central Intelligence Agency News & Information Blog, November 4, 2014.
Over the years there have been more than a few CIA officers held in captivity. Some of these officers died in captivity. One CIA officer, William Buckley, was captured while serving as the CIA Station Chief during an extremely dangerous time in Lebanon. He died after days of horrific torture by his Islamic Jihad captors. Buckley was also an Army veteran of the Korean and Vietnam War as well as a Special Forces officer. See "CIA Remembers Agency Hero William Buckley", Central Intelligence Agency Press Release, March 14, 2014 and a dedication to LTC William Buckley by the Special Forces Association.