Last Updated 12:48 a.m. ET
Libyan rebels took control of large swaths of the capital Tripoli on Sunday with the aid of secretly-armed "sleeper cells", meeting little resistance on their way into the city's center. The opposition's leaders said Muammar Qaddafi's son and one-time heir apparent, Saif al-Islam, has been arrested, and their are several reports that his eldest son, Mohammed Qaddafi, has surrendered.
A rebel leader told Al Jazeera that Qaddafi has refused to surrender, and that his guards shot at rebels as they were closing in, killing one of them. There are many rumors, but the truth of Qaddafi's whereabouts are currently unknown.
"It's over, frizz-head," chanted hundreds of jubilant men and women massed in Green Square, using a mocking nickname of the curly-haired Qaddafi. The revelers fired shots in the air, clapped and waved the rebels' tricolor flag. Some set fire to the green flag of Gadhafi's regime and shot holes in a poster with the leader's image.
President Barack Obama said in a statement late Sunday: "Tripoli is slipping from the grasp of a tyrant. The people of Libya are showing that the universal pursuit of dignity and freedom is far stronger than the iron fist of a dictator. The United States has recognized the Transitional National Council as the legitimate governing authority in Libya."
In a similar statement, the NATO secretary general said the dictator's regime was "clearly crumbling. The sooner Qaddafi realizes that he cannot win the battle against his own people, the better -- so that the Libyan people can be spared further bloodshed and suffering."
Sky News correspondent Alex Crawford reports that along the way of the speedy rebel advance, there was no substantial resistance from the Qaddafi troops. All the evidence suggested the government's soldiers had ditched their uniforms and had simply scarpered.
Rebels take control of parts of Tripoli
Complete coverage: Anger in the Arab World
The rebels advance swept quickly into Green Square, once the symbolic center of Qaddafi's revolution. The regime has held pro-Qaddafi rallies there nearly every night since the revolt began in February, and the historic Red Fort that overlooks the square is a favorite scenic spot for the Libyan leader to deliver speeches to his loyalists. The Green Square has been renamed "Martyrs Square" by many celebrating there.
In a telephone interview with CBS News, Tripoli resident Hana Mohammed, a translator for a foreign embassy in Tripoli, said she had just came back from Green Square, where she said residents were celebrating wildly.
Hana Mohammed said: "It's the moment we've been waiting for 6 months. Yesterday was the worst night... Qaddafi troops were still around and killed many people. Today the rebels have control of all of Tripoli. No words in my dictionary can explain how I feel... I am so excited and happy. It means the future and freedom, I cannot explain it, I feel like I'm in a dream. I never imagined that Qaddafi would be gone in one day, but it is the truth. The people have the power now."
While his whereabouts are currently unknown, Qaddafi made a desperate public plea late Sunday, calling on Libyans to "get out of your homes and stop this from happening. Crawl towards Tripoli. All tribes should take part. Do it or you will become slaves of the French occupiers and their Italian allies. To rebels, return from where you came from. NATO won't protect you from the rage of the Libyan people."
The rebels have claimed they are now in control of all of Tripoli, according to most reports.
Along the way, they freed several hundred prisoners from a regime lockup. The fighters and the prisoners - many looking weak and dazed and showing scars and bruises from beatings - embraced and wept with joy.
Thousands of jubilant civilians rushed out of their homes to cheer the long convoys of pickup trucks packed with rebel fighters shooting in the air. Some were hoarse, shouting: "We are coming for you, frizz-head," a mocking nickname for Qaddafi. In villages along the way that fell to the rebels one after another, mosque loudspeakers blared "Allahu Akbar," or "God is great."
"We are going to sacrifice our lives for freedom," said Nabil al-Ghowail, a 30-year-old dentist holding a rifle in the streets of Janzour, a suburb just six miles west of Tripoli. Heavy gunfire erupted nearby.
As town after town fell and Qaddafi forces melted away, the mood turned euphoric. Some shouted: "We are getting to Tripoli tonight." Others were shooting in the air, honking horns and yelling "Allahu Akbar."
Inside Tripoli, widespread clashes erupted for a second day between rebel "sleeper cells" and Qaddafi loyalists. Rebels fighter who spoke to relatives in Tripoli by phone said hundreds rushed into the streets in anti-regime protests in several neighborhoods.
Libyan state television aired an angry audio message from Qaddafi Sunday night, urging families in Tripoli to arm themselves and fight for the capital.
"The time is now to fight for your politics, your oil, your land," he said. "I am with you in Tripoli - together until the ends of the earth," Qaddafi shouted.
The day's first breakthrough came when hundreds of rebels fought their way into a major symbol of the Qaddafi regime - the base of the elite 32nd Brigade commanded by Qaddafi's son, Khamis. Fighters said they met with little resistance.
Hundreds of rebels cheered wildly and danced as they took over the compound filled with eucalyptus trees, raising their tricolor from the front gate and tearing down a large billboard of Qaddafi.
Inside, they cracked open wooden crates labeled "Libyan Armed Forces" and loaded their trucks with huge quantities of munitions. One of the rebels carried off a tube of grenades, while another carted off two mortars.
"This is the wealth of the Libyan people that he was using against us," said Ahmed al-Ajdal, 27, pointing to his haul. "Now we will use it against him and any other dictator who goes against the Libyan people."
One group started up a tank, drove it out of the gate, crushing the median of the main highway and driving off toward Tripoli. Rebels celebrated the capture with deafening amounts of celebratory gunfire, filling the air with smoke.
Across the street, rebels raided a huge warehouse, making off with hundreds of crates of rockets, artillery shells and large-caliber ammunition. The warehouse had once been using to storage packaged foods, and in the back, cans of beans were still stacked toward the ceiling.
The prisoners had been held in the walled compound and when the rebels rushed in, they freed more than 300 of them.
"We were sitting in our cells when all of a sudden we heard lots of gunfire and people yelling 'Allahu Akbar.' We didn't know what was happening, and then we saw rebels running in and saying 'We're on your side.' And they let us out," said 23-year-old Majid al-Hodeiri from Zawiya. He said he was captured four months ago by Qaddafi's forces and taken to base. He said he was beaten and tortured while under detention.
Many of the prisoners looked disoriented as they stopped at a gathering place for fighters several miles away from the base. Some had signs of severe beatings. Others were dressed in tattered T-shirts or barefoot. Rebels fighters and prisoners embraced.
From the military base, about 16 miles west of Tripoli, the convoy pushed on toward the capital.
Mahmoud al-Ghwei, 20 and unarmed, said he had just came along with a friend for the ride .
"It's a great feeling. For all these years, we wanted freedom and Qaddafi kept it from us. Now we're going to get rid of Qaddafi and get our freedom," he said.
At nightfall, the fighters reached Janzour, a Tripoli suburb. Along the way, they were greeted by civilians lining the streets and waving rebel flags. One man grabbed a rebel flag that had been draped over the hood of a slow-moving car and kissed it, overcome with emotion.
The uprising against Qaddafi broke out in mid-February, and anti-regime protests quickly spread across the vast desert nation with only 6 million people. A brutal regime crackdown quickly transformed the protests into an armed rebellion. Rebels seized Libya's east, setting up an internationally recognized transitional government there, and two pockets in the west, the port city of Misrata and the Nafusa mountain range.
Qaddafi clung to the remaining territory, and his forces failed to subdue the rebellion in Misrata, Libya's third-largest city, and in the Nafusa mountains. Since the start of August, thousands of rebel fighters, including many who fled Qaddafi-held cities, joined an offensive launched from the mountains toward the coast.
Rebels said Saturday that they had launched their first attack on Tripoli in coordination with NATO, and gunbattles and mortar rounds rocked the city. NATO aircraft also made heavier than usual bombing runs after nightfall, with loud explosions booming across the city.
On Sunday, more heavy machine gun fire and explosions rang out across the capital with more clashes and protests.
Government minders in a hotel where foreign journalists have been staying in Tripoli armed themselves on Sunday in anticipation of a rebel take over. The hotel manager said he had received calls from angry rebels threatening to charge the hotel to capture the government's spokesman, Moussa Ibrahim.