Rebels seized control of sections of Syria's international borders and torched the main police headquarters in the heart of old Damascus, advancing relentlessly after the assassination of President Bashar al-Assad's closest lieutenants. The battle for parts of the capital raged into the early hours of Friday, July 20, 2012, , with corpses piled in the streets. In some neighborhoods, residents said there were signs the government's presence was diminishing.

Rebels also claimed control of at least two border crossings into Turkey at Bab al-Hawa and Jarablus, in what appeared to have been a coordinated campaign to seize Syria's frontiers.

The operations to seize the border checkpoints appear to show a level of coordination and effectiveness hitherto unseen from the rebels, who have been outgunned and outnumbered by the army throughout the 16-month conflict.

Footage filmed by rebels at the Bab al-Hawa border crossing with Turkey showed them climbing onto rooftops and tearing up a poster of Assad.

"The crossing is under our control. They withdrew their armored vehicles," said a rebel fighter who would only be identified as Ali, being treated for wounds on the Turkish side.

Two officers in the rebel Free Syrian Army said fighters were keeping themselves busy into the early hours of Friday, dismantling border computer systems, seizing security records and emptying the shelves of the duty-free shop.

At least 30 government tanks in the area had not mobilized to try to recapture the border post, according to Ahmad Zaidan, a senior Free Syrian Army commander.

"Three patrol cars came to the site and were hit by roadside bombs," said activist Abu Rateb by telephone. "I saw three bodies in one car. Others said dozens of security men and shabbiha (pro-Assad militia) lay dead or wounded along Khaled bin al-Walid street, before ambulances took them away.

Government forces have responded by blasting at rebels in their own capital with helicopter gunships and artillery stationed in the mountains overlooking it.

Activists in Damascus said rebels were now in control of the capital's northern Barzeh district, where troops and armored vehicles had pulled out.

The army had also pulled out of the towns of Tel and Dumair north of Damascus after taking heavy losses, they said. But they said troops were hitting the western district of Mezzeh with heavy machineguns and anti-aircraft guns overnight.

Shelling could be heard on the southwestern suburb of Mouadamiyeh from hills overlooking the city where the Fourth Division, commanded by Assad's brother Maher, is based, he said.

Syrian television showed the bodies of about 20 men in T-shirts and jeans with weapons lying at their sides, sprawled across a road in the capital's Qaboun district. It described them as terrorists killed in battle.