Tanks opened fire at rebels trying to storm Muammar Gaddafi's main compound in Tripoli today, although he appeared to have vanished a day after the lightning advance by his opponents into the city.
The international community meanwhile called on him to step down as euphoric residents celebrated in the Green Square, the symbolic heart of the Gaddafi regime.
Rebel spokesman Mohammed Abdel-Rahman, who was in Tripoli, cautioned that pockets of resistance remained Gaddafi loyalists and that as long as Gaddafi was on the run the "danger is still there."
The clashes broke out at Gaddafi's command centre known as Bab al-Aziziya early today when government tanks emerged from the complex and opened fire at rebels trying to get in.
Tripoli resident Moammar al-Warfali, whose family home is next door, said there appeared to be only a few tanks belonging to the remaining Gaddafi forces that have not fled or surrendered.
"When I climb the stairs and look at it from the roof, I see nothing at Bab al-Aziziya," he said. "Nato has demolished it all and nothing remains."
State TV broadcast desperate audio pleas by Gaddafi for Libyans to defend his regime. Opposition fighters captured his son and one-time heir apparent, Saif al-Islam, who along with his father faces charges of crimes against humanity at the International Criminal Court in the Netherlands. Another son was under house arrest.
"It's over, frizz-head," chanted hundreds of jubilant men and women massed in Green Square late on Sunday, using a mocking nickname of the curly-haired Gaddafi. The revellers fired shots in the air, clapped and waved the rebels' tricolour flag. Some set fire to the green flag of Gaddafi's regime and shot holes in a poster with the leader's image.
But Gaddafi's defiance in a series of angry audio messages raised the possibility of a last-ditch fight over the capital, home to two million people. Gaddafi, who was not shown in the messages, called on his supporters to march in the streets of the capital and "purify it" of "the rats."
Nato officials promised planes would continue to conduct regular patrols over Libya despite the latest rebel successes.
Gaddafi's former right-hand man, who defected last week to Italy, said the leader would not go easily.
"I think it's impossible that he'll surrender," Abdel-Salam Jalloud said, adding that "He doesn't have the courage, like Hitler, to kill himself."
Jalloud, who was Gaddafi's closest aide for decades before falling out with the leader in the 1990s, fled Tripoli on Friday.
The startling rebel breakthrough, after a long deadlock in Libya's six-month-old civil war, was the culmination of a closely coordinated plan by rebels, Nato and anti-Gaddafi residents inside Tripoli, rebel leaders said. Rebel fighters from the west swept over 20 miles in a matter of hours on Sunday, taking town after town and overwhelming a major military base as residents poured out to cheer them. At the same time, Tripoli residents secretly armed by rebels rose up.
When rebels reached the gates of Tripoli, the special battalion entrusted by Gaddafi with guarding the capital promptly surrendered. The reason: Its commander, whose brother had been executed by Gaddafi years ago, was secretly loyal to the rebellion.
President Barack Obama said Libya was "slipping from the grasp of a tyrant" and urged Gaddafi to relinquish power to prevent more bloodshed.
"The future of Libya is now in the hands of the Libyan people," he said.
South Africa, which led failed African Union efforts to mediate between the rebels and Gaddafi, refused to offer support to the rebels, saying it wants to see a unity government put in place as a transitional authority. But Foreign Minister Maite Nkoana-Mashabane said she did not envision a role for Gaddafi on such a transitional body, saying he had told AU mediators four months ago he was ready to give up leadership.
She also said repeatedly that South Africa has sent no planes to Libya to evacuate Gaddafi, has received no request from him for asylum and is involved in no efforts to extricate him.
The uprising against Gaddafi broke out in mid-February, inspired by successful revolts in Egypt and Tunisia. A brutal regime crackdown quickly transformed the protests into an armed rebellion. Rebels seized Libya's east, setting up an internationally recognised transitional government there, and two pockets in the west, the port city of Misrata and the Nafusa mountain range.
Gaddafi clung to the remaining territory, and for months neither side had been able to break the other.
In early August, however, rebels launched an offensive from the Nafusa Mountains, then fought their way down to the Mediterranean coastal plain, backed by Nato airstrikes, and captured the strategic city of Zawiya.
The rebels' leadership council, based in the eastern city of Benghazi, sent out mobile text messages to Tripoli residents, proclaiming, "Long live Free Libya" and urging them to protect public property. internet service returned to the capital for the first time in six months.
Gaddafi is the Arab world's longest-ruling, most erratic, most grimly fascinating leader - presiding over this North African desert nation with vast oil reserves and just 6 million people. For years, he was an international pariah blamed for the 1988 bombing of a Pan Am jumbo jet over Lockerbie that killed 270 people.