Hundreds of men, including many non-Afghans, surrendered near Kunduz and were being held as enemy combatants at Qala-i-Jangi fortress by the Afghan Northern Alliance (United Islamic Front for the Salvation of Afghanistan) forces for an interrogation by the American Central Intelligence Agency (CIA) personnel interested in al-Qaeda suspects. The prisoners violently revolted and the ensuing fighting escalated into one of the bloodiest engagements of the conflict. It took Northern Alliance fighters, assisted by British and American special forces and air support, six days to quell the revolt.