Libyan leader Col. Muammar Gaddafi is vowing to fight on even though NATO-backed forces have seized control of much of Tripoli, including Gaddafi’s main compound. But in a defiant message to supporters, Gaddafi vowed last night “martyrdom” or victory, and urged loyalists to fight the rebels. Gaddafi’s whereabouts remain unknown and his powerful sons unaccounted for despite rebel claims that the sons had been seized. United Nations Libyan envoy Ibrahim Dabbashi praised the rebel advances.

Ibrahim Dabbashi, Libyan U.N. envoy: “The regime of Gaddafi has already fallen. It doesn’t exist since the last two days, because none of the Gaddafi regime institutions was working during the last days. It is only a few high officials who are escaping from place to another inside Tripoli, and they are struggling to keep themselves safe.”

While supporters of the rebels have held celebrations across Libya, many analysts say the fighting could continue for weeks or months. Many questions remain unanswered about who controls Libya’s vast arms depots.