Having taken over three major surrounding towns, Libyan rebels moved into Tripoli, where heavy fighting was reported late Saturday night. A rebel leader confirmed that they were "coordinating the attacks inside," that more forces were advancing from outside, and that this was "zero hour." The rebels also confirmed success in clearing out the last of Muammar Gaddafi's forces from the center of Zawiyah, 30 miles west of Tripoli. Meanwhile, another major government official has reportedly defected from the regime—the third in one week—indicating that Gaddafi's power is slipping. Rebel leaders are optimistic that his demise is near, even as other reports say his loyalists are armed and blocking off Tripoli's streets in preparation for battle. A spokesman for Gaddafi's regime insisted the leader would remain in power and called on rebels to surrender. Gaddafi has also appeared on state TV, congratulating Libyans on defeating "the rats."