The rebels have now placed the Libyan independence flag atop Gadhafi’s home. That news comes as a U.S. State Department spokesperson confirmed the gains. “There’s no question that the Gadhafi regime has nearly collapsed,” said State Department spokeswoman Victoria Nuland.

Rebels surged into the Libyan capital Sunday night, meeting only sporadic resistance from troops loyal to Col. Muammar el-Qaddafi and setting off raucous street celebrations by residents hailing the end of his 42 years in power.

The rebel leadership announced that insurgents had captured two of Colonel Qaddafi’s sons, including Seif al-Islam, his heir apparent, as rebel fighters entered the city’s central Green Square, where joyous Libyans tore down posters of Colonel Qaddafi and stomped on them. The leadership also announced that the elite presidential guard protecting the Libyan leader had surrendered and that they controlled many parts of the city, not including Colonel Qaddafi’s leadership compound.

The National Transitional Council, the rebel governing body, issued a mass text message saying, “We congratulate the Libyan people for the fall of Muammar Qaddafi and call on the Libyan people to go into the street to protect the public property. Long live free Libya.”

Officials loyal to Qaddafi insisted that the fight was not over, and there were clashes between rebels and government troops early Monday morning. But NATO and American officials said that the Qaddafi’s government’s control of Tripoli, which had been its final stronghold, was now in doubt.

“Clearly, the offensive for Tripoli is underway,” the State Department spokeswoman Victoria Nuland said in a statement. The statement said “Qaddafi’s days are numbered,” and urged the rebel leadership to prepare for a transfer of power and “maintain broad outreach across all segments of Libyan society and to plan for a post-Qaddafi Libya.”