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The streets where rebel fighters bombarded snipers loyal to Muammar Qaddafi were strewn with bullet-ridden corpses from both sides Thursday. Streams of blood ran down the gutters and turned sewers red.

By sundown the rebels appeared to have won the battle for the Abu Salim neighborhood, next to Qaddafi's captured Tripoli compound, but the fallen dictator continued to elude them. Speaking from an unknown location, he exhorted his supporters to fight on.

"Don't leave Tripoli for the rats. Fight them, and kill them," Qaddafi said in a new audio message broadcast on Al-Ouroba TV, a Syria-based satellite station.

Outside his Bab al-Aziziya compound, which rebels captured Tuesday, there was another grim scene -- one that suggested mass, execution-style killings of civilians.

About two dozen bodies -- some with their hands bound by plastic ties and with bullet wounds to the head -- lay scattered on grassy lots in an area where Qaddafi sympathizers had camped out for months.

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The identities of the dead were unclear, but they were in all likelihood activists who had set up an impromptu tent city in solidarity with Qaddafi in defiance of the NATO bombing campaign.

Five or six bodies were in a tent erected on a roundabout that had served as a field clinic. One of the dead still had an IV in his arm, and another body was completely charred, its legs missing. The body of a doctor, in his green hospital gown, was found dumped in the canal.

It was unclear who was responsible for the killings.

Rebels have seized most of Tripoli since sweeping into the capital on Sunday, and on Thursday they announced that their leadership was moving into the capital. The rebel National Transitional Council has been based in the eastern city of Benghazi, which fell to rebel forces early in the conflict.

"In the name of the martyrs ... I proclaim the beginning ... of the work of the executive office in a free Tripoli as of this moment," Ali Tarhouni, the council's finance minister, told reporters in Tripoli.

"I have a final message for everyone who is still carrying arms against the revolution," he said, "to let go of their arms and go back to their homes, and we promise not to take revenge against them."

The rebels know they cannot declare a full victory in the 6-month-old civil war as long as Qaddafi has not been captured or killed. There was no sign of the leader or his sons, despite rumors that swirled around the battlefield that they may be hiding inside some of the besieged buildings in Abu Salim.

The neighborhood, where battles have raged for days, is thought to be the last major stronghold of regime brigades in Tripoli, though there has also been ongoing fighting around the airport. Many of the pro-Qaddafi forces in Abu Salim are believed to have fled his Bab al-Aziziya compound after rebels captured it Tuesday, and the neighborhood is among the few places in Tripoli where pro-Qaddafi graffiti has not been painted over.

Rebel fighters moved methodically through the neighborhood -- some on foot, wearing shorts and carrying machine guns, and others in long lines of pickup trucks with weapons mounted on the back. They fired anti-aircraft guns and rockets, trying to clear buildings of Qaddafi defenders.

Some of the bodies in the streets were on fire. The rebels covered their own with blankets and left the bullet-riddled bodies of their foes exposed.

The air was clogged with deafening explosions from mortars, the whistle of sniper fire and smoke from burning buildings and ammunition.

Civilians were in some of the buildings and caught up in the crossfire.

A mother ran out of one the buildings under siege, screaming: "My son needs first aid." Behind her, the building's glass windows were shattered and black smoked poured out of a burning apartment.

Amid the din, the call to prayer wafted out from neighborhood mosques.

The rebels, many from the western, rebel-held city of Misrata, were spurred on by rumors that one of Qaddafi's sons might be hiding in the buildings.

"Today is a crucial moment. This huge resistance suggests there is a big person there," said Youssef Aradat, a rebel fighter with a beard and aviator sunglasses. "It is a matter of hours. Now we can kill him. We will go room by room, flat by flat, street by street."

Qaddafi has repeatedly vowed to fight until "victory or martyrdom."

"Take over the rooftops, the mosques, the side streets; there will be no safe place for the enemies," he said in the audio message. He warned that the rebels will try to go into his supporters' homes and rape women. "They will enter your houses and deprive you of your honor."

In Washington, the Pentagon pushed back on assertions that either NATO or the U.S. military is actively engaged in a manhunt for Qaddafi, underscoring ongoing sensitivities over the strict parameters of the U.N. mission there.

Marine Col. David Lapan said the U.S. is conducting aerial surveillance of Libya in support of NATO's military mission to protect civilians from attack by government forces. But he said this does not amount to targeting Qaddafi, and that it is not NATO's mission to target or hunt down individuals.

That statement conflicted with comments by British Defense Secretary Liam Fox, who said Thursday that NATO intelligence and reconnaissance assets are being used to try to hunt down Qaddafi.

Qaddafi's spokesman Moussa Ibrahim, in a call to AP's Cairo office, said Qaddafi was still in Libya and his morale was high. Ibrahim refused to say where Qaddafi was hiding, but said he "is indeed leading the battle for our freedom and independence."

Ibrahim, whose voice was clearly recognizable, said he was also in hiding in Libya and constantly on the move.

"All of the leader's family are fine," Ibrahim said, adding that top military and political aides remained with Qaddafi.

Ibrahim claimed Qaddafi's forces controlled a "good portion" of the capital -- a claim that contradicts what reporters can see -- and other cities and towns.

In Abu Salim, the hours-long barrage ended at sunset. Rebel fighters went door to door through largely deserted apartment buildings, occasionally dragging out suspected regime loyalists.

Some were dark-skinned men wearing cut-off camouflage and T-shirts. Their hands were tied behind their backs before they were driven away. The rebels have long claimed Qaddafi had been hiring mercenaries from sub-Saharan Africa to bolster his army.

Some rebels looted the buildings, taking computers from a devastated fire station and printers from a nearby market area.

Rebels say one of their key targets now is Qaddafi's hometown of Sirte, about 250 miles from Tripoli, but capturing that city would not be easy because Qaddafi's fellow tribesmen were expected to put up a fierce fight.

Opposition leaders have said they were trying to negotiate a peaceful surrender of the city. The rebels said the supply lines to Sirte would be too long and they are short of funds and supplies.

The rebels have appealed to foreign governments for help freeing up funds Qaddafi's regime has amassed around the world. The U.S. and South Africa reached a deal Thursday that will release $1.5 billion in frozen Libyan assets in American banks, and Italy was preparing to release $505 million in frozen assets in Italian banks in what Premier Silvio Berlusconi called a first payment.

Four Italian journalists taken at gunpoint in Tripoli were freed Thursday in a raid on the house where they were being held, an official said.

Beyond the capital, rebels have seized several parts of Sebha, a Qaddafi stronghold deep in the south, according to rebel official Adel al-Zintani, who is in daily telephone contact with rebel commanders in the desert city.

Fawzi Abu Ketf, the council's deputy defense minister, said fighting was raging outside Bin Jawad, 400 miles east of Tripoli, but he had no details.

Qaddafi loyalists ambushed rebels advancing toward Bin Jawad on Wednesday, killing at least 20 of them. The ambush showed that pro-regime forces retain the ability to strike back even as the rebels tighten their control over the nation's capital.

Mustafa Abdel-Jalil, head of the National Transitional Council, called on people living in loyalist-held towns to join the fight against Qaddafi's soldiers.

"I am appealing to the areas not yet liberated to join the revolution," he told reporters in Benghazi. "There is no excuse for them not to join."