Libyan Rebels Control Much of Tripoli, Gadhafi Whereabouts Unknown The rebels say they have reached surrounded Gadhafi compound.

Aug. 21, 2011 -- Rebel forces took control of much of Tripoli tonight, and thousands flooded the streets of the Libyan capital and other cities around the country to celebrate what they hope will be the end of Moammar Gadhafi's 42-year reign.

"We were waiting for the signal and it happened," Nour Eddin Shatouni, a 50-year-old engineer celebrating the apparent collapse of the strongman's regime, told The Associated Press. "All mosques chanted 'God is great' all at once. We smelled a good scent, it is the smell of victory. We know it is the time."

The Transitional National Council (NTC), the administration set up by the rebel forces, claimed that three of the Libyan strongman's sons have either been captured or surrendered.

Muhammad Gadhafi, son of the Libyan leader, told Al Jazeera in a weepy phone call that he had surrendered to opposition forces. Crying on the phone, he said that his house was surrounded by gunfire and he was under house arrest.

Shortly before that phone call, his brothers Seif al Islam and Saadi, were captured by rebel forces in Tripoli, according to the NTC. Seif al Islam, like his father, has been indicted on charges of crimes against humanity by the International Criminal Court.

ICC representatives will meet Monday with the transitional forces to discuss how Seif al Islam will be transferred to the Hague, ICC chief prosecutor Luis Moreno-Ocampo told The Associated Press.

Rebel forces have surrounded the Gadhafi compound, Bab al Aziziya, a representative of the rebel government told ABC News and gunfire has been heard outside the compound.

Mohamad al Akari, an NTC advisor, said that if Moammar Gadhafi is still in Tripoli, they believe he is in Bab al Aziziya.

"Tonight it's over," Akari said.

The NTC also claimed that members of Gadhafi's presidential guard have surrendered to the rebel forces.

Libyan rebel forces gathered in Green Square in the heart of Tripoli, but there were isolated clashes with government forces and snipers throughout the city, according to multiple reports.

In Benghazi, in eastern Libya, crowds set off fireworks, waving flags and cheering for Gadhafi's departure.

President Obama said the day's events proved that there was only one choice for Gadhafi: to give up power and let the Libyan people decide their own future.

"The surest way for the bloodshed to end is simple: Moammar Gadhafi and his regime need to recognize that their rule has come to an end," Obama said. "Gadhafi needs to acknowledge the reality that he no longer controls Libya. He needs to relinquish power once and for all."

The secretary general of NATO, whose air strikes Gadhafi blamed for the rebels' success, also said Gadhafi's regime was "clearly crumbling."

NATO Secretary-General Anders Fogh Rasmussen said air strikes would continue if government troops make "any threatening moves toward the Libyan people."

Gadhafi's whereabouts were unknown, but audiotapes of the strongman were broadcast on state television this evening that his forces would not give up and would "fight until the last blood drop."

"How come you allow Tripoli the capital, to be under occupation once again?" he said in the broadcast, in which he was not shown. "The traitors are paving the way for the occupation forces to be deployed in Tripoli."

Earlier today, rebel forces pushed into the western outskirts of the Libyan capital without meeting any resistance. The rebels reached Janzour, a Tripoli suburb, around nightfall today and were greeted by civilians waving rebel flags.

In a brief gunbattle only hours earlier, the same rebel force of hundreds drove elite forces, led by another of Gadhafi's sons, out of a major military base outside Tripoli. The rebels captured truckloads of weapons and advanced toward Tripoli, according to the AP.

Gunfire and explosions were heard throughout the night inside the capital, where fighting flared up between Gadhafi forces and what the opposition called "sleeper cells" of rebels who had waited for the opposition's main forces to lay siege to the city.

This morning there was a threatened assault on the Rixos Hotel, where many foreign journalists are staying. The entire staff, including the manager, fled, leaving about 20 journalists stranded. For a while the building was surrounded by constant machine gun fire, but troops never entered the hotel and eventually the fighting ceased.

The rebels hit Tripoli from three fronts and were helped by NATO war planes enforcing a UN resolution to protect civilians.

Libyan government spokesman Moussa Ibrahim said "the death toll [in Tripoli] is beyond imagination," and said NATO has the blood of innocent Libyans on its hands because of the cover it provided for the rebel forces.

"NATO kills anything that moves," he said, blaming NATO for the "true tragic event taking place in Tripoli."

Earlier in the day, Ibrahim had singled out the leaders of the United States, the United Kingdom and France for blame.

"We hold Mr. Obama, Mr. Cameron and Mr. Sarkozy morally responsible for every single unnecessary death that takes place in this country," Ibrahim said.

He also insisted that Tripoli was well defended from the rebels.

"Tripoli is well protected and we have thousands upon thousands of professional soldiers who are ready to defend this city," Ibrahim said.

He warned that the fighting would continue if there is no ceasefire.

"We are going to fight on unless everybody agrees on a ceasefire because as a dignified nation we have our freedom, we have our honor and we know that people even scared in their houses at this very moment, they do not want us to give up," Ibrahim said.

ABC News' Linda Albin, Jeffrey Kofman and The Associated Press contributed to this report.