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Associated Press
In this photo taken during a government-organized tour, a Syrian man, background, looks at cars burned during a clashes between Syrian troops and rebels in the Midan district, in the southern part of Damascus, Syria, Friday, July 20, 2012. Syrian troops and tanks on Friday drove rebels from a Damascus neighborhood where some of the heaviest of this week's fighting in the capital left cars gutted and fighters' bodies in the streets. Hundreds of people were killed in a single day, activists said, as the military struggles to regain momentum after a stunning bombing against the regime's leadership. (AP Photo/Bassem Tellawi)

BEIRUT — Rebels pressed their guerrilla fight to topple Syria's regime deeper into the capital on Friday, ambushing troops and attacking police stations as thousands of terrified civilians fled to Lebanon and Iraq to escape some of the worst violence of the 16-month conflict.

The two-day death toll was more than 470 people, marking some of the deadliest of the uprising.

The U.N. refugee agency said between 8,500 and 30,000 Syrians had entered Lebanon in the past three days, and thousands of Iraqis have also returned home, a bitter trip for many who fled to Syria from their own country's civil war.

In Damascus, Syrian forces recaptured one battle-scarred neighborhood and proudly showed reporters the dead bodies of rebel fighters lying in rubble-strewn streets.

But rebels said they withdrew to expand their guerrilla war, pointing to the difficulty both sides will have in achieving victory in Damascus, the central bastion of President Bashar Assad's rule.

Fighting has flared across Syria this week, as battles have ravaged Damascus neighborhoods, death tolls have skyrocketed, border crossings have fallen to rebel fighters and a rebel bomb attack killed top members of Assad's regime.

Assad's national security chief, Gen. Hisham Ikhtiyar, died Friday from wounds sustained in the bombing Wednesday that killed three others, including the defense minister and Assad's brother-in-law. All were key to the government's efforts to stamp out the insurgency.

The fighting has shattered parts of Damascus, with rebels attacking at least two police stations and government troops pounding rebel districts with mortars, machine-guns and attack helicopters.

The clashes echoed those seen elsewhere in Syria, with lightly armed, disorganized rebels avoiding direct battles with better-equipped government troops while launching ambushes on their convoys and checkpoints.

The regime, for its part, has deployed overwhelming firepower, shelling from afar and sending attack helicopters that rebel weapons can't reach.

"We often make tactical retreats so that there is no face-to-face confrontation," a rebel named Mohammed from the Eagles of Damascus brigade said via Skype. "It's like gang warfare. We pull out so we can hit in a different place or plan an attack on a regime checkpoint."

Like most rebels, his group has only assault rifles and rocket-propelled grenades, but lacks long-range weapons, leaving them helpless against government shelling and helicopter strikes.

They also lack ammunition.

"If we had all the ammunition we needed, we would have liberated the capital in two days," he said, asking that his full name not be published for fear of government reprisals.