TRIPOLI, Libya - (AP) - Libyan rebels raced into Tripoli Sundayand met little resistance as Moammar Gadhafi's defenders meltedaway and his 42-year rule rapidly crumbled. The euphoric fighterscelebrated with residents of the capital in Green Square, thesymbolic heart of the fading regime.

Gadhafi's whereabouts were unknown, though state TV broadcasthis bitter pleas for Libyans to defend his regime. Oppositionfighters captured his son and one-time heir apparent, Seifal-Islam, who along with his father faces charges of crimes againsthumanity at the International Criminal Court in the Netherlands.Another son was in contact with rebels about surrendering, theopposition said.

"It's over, frizz-head," chanted hundreds of jubilant men andwomen massed in Green Square, using a mocking nickname of thecurly-haired Gadhafi. The revelers fired shots in the air, clappedand waved the rebels' tricolor flag. Some set fire to the greenflag of Gadhafi's regime and shot holes in a poster with theleader's image.

By the early hours of Monday, rebels controlled large parts ofthe capital. They set up checkpoints alongside residents - many ofthem secretly armed by rebel smugglers in recent weeks. But pocketsof pro-Gadhafi fighters remained: In one area, Associated Pressreporters with the rebels were stopped and told to take a differentroute because of regime snipers nearby.

"We were waiting for the signal and it happened," said NourEddin Shatouni, a 50-year-old engineer who was among the residentswho flowed out of their homes to join the celebrations. "Allmosques chanted 'God is great' all at once. We smelled a goodscent, it is the smell of victory. We know it is the time."

The seizure of Green Square held profound symbolic value andmarked a stunning turn in the tide of the 6-month-old Libyan civilwar. The regime has held pro-Gadhafi rallies there nearly everynight since the revolt began in February, and Gadhafi deliveredspeeches to his loyalists from the historic Red Fort that overlooksthe square.

The sweep into the capital came after the rebel fightersadvanced 20 miles from the west in a matter of hours. They tooktown after town and overwhelmed a major military base meant todefend Tripoli, 16 miles from the city. All the way, they metlittle resistance and residents poured out on the streets towelcome them.

In a series of angry and defiant audio messages broadcast onstate television, Gadhafi called on his supporters to march in thestreets of the capital and "purify it" of "the rats." He wasnot shown in the messages.

His defiance raised the possibility of a last-ditch fight overthe capital, home to 2 million people. Government spokesman MoussaIbrahim claimed the regime has "thousands and thousands offighters" and vowed: "We will fight. We have whole cities on oursides. They are coming en masse to protect Tripoli to join thefight."

But it appeared that Gadhafi's military was abandoning himquickly.

The rebels' way into Tripoli was opened when the military unitin charge of protecting Gadhafi and the capital surrendered,ordering his troops to drop their weapons, the rebel informationminister Mahmoud Shammam said.

In a sign of the coordination among rebels, as the main forcemoved into the city from the west, a second force of 200 oppositionfighters from the city of Misrata further east landed by boat inthe capital. They brought weapons and ammunition for Tripoliresidents who join the rebellion, said Munir Ramzi of the rebels'military council in Misrata.

NATO Secretary-General Anders Fogh Rasmussen said Gadhafi'sregime was "clearly crumbling" and that the time to create a newdemocratic Libya has arrived.

The sooner Gadhafi "realizes that he cannot win the battleagainst his own people, the better," he said in a statement,adding that NATO will continue to strike his troops if they make"any threatening moves toward the Libyan people."

In a statement early Monday, President Barack Obama said the wayto prevent more bloodshed was for Gadhafi "to relinquish poweronce and for all." Obama said the rebel leaders must pursue apeaceful transition to democracy.

It was a stunning reversal for Gadhafi, who earlier this monthhad seemed to have a firm grip on his stronghold in the westernpart of Libya, despite months of NATO airstrikes on his military.Rebels had been unable to make any advances for weeks, bogged downon the main fronts with regime troops in the east and center of thecountry.

Gadhafi is the Arab world's longest-ruling, most erratic, mostgrimly fascinating leader - presiding for 42 years over this NorthAfrican desert republic with vast oil reserves and just 6 millionpeople. For years, he was an international pariah blamed for the1988 bombing of a Pan Am jumbo jet over Lockerbie, Scotland, thatkilled 270 people. After years of denial, Gadhafi's Libyaacknowledged responsibility, agreed to pay up to $10 million torelatives of each victim, and declared he would dismantle allweapons of mass destruction.