Libyan rebels are clashing with Col. Muammar Gaddafi’s forces in an attempt to gain control of strategic oil refineries and further isolate the capital city of Tripoli. On Wednesday, the rebels launched an assault on a refinery in the city of Zawiyah, forcing hundreds of refugees to flee. A similar effort in the city of Brega has reportedly left 18 rebel fighters dead and 33 others wounded. Residents say electricity has been cut in the capital Tripoli, where the Gaddafi regime is struggling to retain control. East of the city, rebels are now claiming to have discovered a mass grave containing 150 civilian bodies.