The fighting in Tripoli came as the opposition reportedly seized control of Misurata, with witnesses saying people were honking their horns and raising pre-Gadhafi flags from the monarchy to celebrate.

Misurata would be the first major city in the west to fall to antigovernment forces, which have mainly been concentrated in the east. Faraj al-Misrati, a local doctor, said six residents had been killed and 200 injured since Jan. 18, when protesters attacked offices and buildings affiliated with Col. Gadhafi’s regime.

New videos posted by Libya’s opposition on Facebook also showed scores of antigovernment protesters raising the flag from the pre-Gadhafi monarchy on a building in Zawiya, on the outskirts of Tripoli. Another showed protesters lining up cement blocks and setting tires ablaze to fortify positions on a square inside the capital. The footage couldn’t be independently confirmed…

What also worries them is the danger that tribes could lay claim to the country’s energy facilities. The main oil fields and production sites are in areas of the country dominated by smaller tribes that lack the strength to seize them for themselves. But the two main export pipelines—one going east and the other west—both run through territory controlled by more powerful groups.