In Syria, fighting rages for third day across Damascus BEIRUT - Fighting spread in a third day of clashes across Damascus, with a rebel commander declaring that insurgents were pushing for the "liberation" of Syria's capital and President Bashar Assad reportedly pulling troops from the border with Israel to defend the city. Skirmishes were reported Tuesday in several additional Damascus neighborhoods. Residents told of the sound of automatic weapons fire, artillery and helicopter gunships just days before the start of Ramadan, the monthlong fasting period for Muslims. There were unconfirmed reports that rebels had shot down a military helicopter in the northern suburb of Barza. "The situation is really difficult today ... shelling, sounds of gunfire," said one opposition sympathizer reached in Damascus by telephone. People are trying to run away. But the snipers shoot madly. Even inside Damascus you see helicopters and you hear them. As the battles raged, the highest-ranking diplomat to defect from the government said that Assad would not hesitate to use the nation's stash of chemical weapons on Syrian rebels to avoid defeat. "Bashar al Assad's regime is like a cornered and wounded wolf," Nawaf Fares, the ambassador to Iraq who defected last week, told the BBC. It will do anything to survive. For months, rebel forces had spoken of their desire to bring the battle to Assad's nerve center. There have been some reports of insurgent fighters filtering into Damascus, which has seen an influx of people displaced by violence elsewhere. In recent weeks, clashes near the capital had been on somewhat of an uptick, though mostly in restive suburbs such as Duma. But it was difficult to determine whether the clashes signaled an all-out insurrection in the capital or unsynchronized eruptions in restive neighborhoods. Continued heavy conflict in the capital could raise doubt about Assad's ability to hold on to power among Syria's merchant class and minorities, including Christians and members of his Alawite sect. With Damascus relatively quiet, these key groups have generally continued to back Assad as the 16-month conflict has gone from street protests to scattered fighting to an all-out insurgency across a broad swath of the nation. Opposition activists were calling this week's fighting the fiercest to date in Damascus, and a potential turning point in the conflict. A senior figure in the Free Syrian Army, the main insurgent umbrella group, declared that the "battle for the liberation of Damascus has begun," according to a Lebanese television website. "We have a clear plan to control the whole of Damascus," said Col. Qassim Saad Eddine of the Free Syrian Army, the website said. We have only light weapons, but it's enough. However, the fighting seemed limited to several neighborhoods, including longtime bastions of the opposition. The government maintained control of key state installations and thoroughfares. Military reinforcements were said to have been brought into the capital and rushed to battleground districts. Video from the capital showed armored vehicles rumbling down main roads. One source of military reinforcement forces may have been the southern section of Syria bordering the Israeli-occupied Golan Heights, which has largely remained quiet for decades. The head of Israeli military intelligence, Maj. Gen. Aviv Kochavi, told lawmakers Tuesday that Assad, with more pressing concerns than those posed by Israel, had pulled troops from the Golan area and reassigned them to the capital. "Assad removed forces from the Golan Heights region to Damascus because he is not concerned conflict will emerge with Israel," the intelligence chief said. Syria's armed forces are already dealing with the deleterious effects of large-scale defections - more than 10,000 troops, by some accounts - and a withering conflict that has cost the lives of more than 2,600 members of the military and security forces. On Tuesday, machine-gun fire was reported near the heart of Damascus in Saba Bahrat Square and nearby Baghdad Street. Video from the capital showed black smoke billowing from several neighborhoods, the apparent result of explosions and fires. The opposition said government forces were using attack helicopters and shelling opponents. Video posted on the Internet appeared to show tanks rumbling in the district of Midan, not far from the old walled city, and a wellspring of violence this week. The official Syrian Arab News Agency said authorities "continue to chase down an armed terrorist group in the outskirts" of Midan, "inflicting heavy losses in the terrorists' ranks." The government typically refers to the rebels as terrorists. Violence was also reported in the northeastern district of Qaboun, where government forces attacked overnight with helicopters, said one opposition activist reached by telephone. The official news agency said rebels fired mortar rounds and rocket-propelled grenades at an electricity converter station in Qaboun. The Local Coordination Committees, an opposition group, reported at least 30 people killed Tuesday in greater Damascus, many as a result of government fire. The casualty count and other details could not be independently verified because journalists' access to Syria is limited. Special correspondent Sandels reported from Beirut and Times staff writer McDonnell from Istanbul, Turkey. News assistant Batsheva Sobelman in The Times' Jerusalem bureau contributed to this report.