BEIRUT -- Syrian authorities were sending reinforcements to strife-torn Aleppo, opposition activists said Wednesday, as outgunned rebels in the northern city tried to deliver a potentially decisive blow to the government of President Bashar Assad.
Street battles were ongoing in several neighborhoods, including districts close to the gates of the old city, with government forces shelling rebel-occupied quarters with artillery and helicopter gunships, the activists said. Many residents had fled or remained indoors in the city of 2 million, they said.
Parts of Aleppo are "a ghost city," said one opposition activist in Aleppo reached via Skype. "The people are scared of going out in the streets," noted the activist, who said he had visited Salahuddin, said to be under the control of rebels.
"There are destroyed buildings there and injuries and deaths," said the activist, who asked not to be named for security reasons.
In the video below, uploaded by opposition activists, rebels have torched what appears to be a police station. Thick black smoke is seen billowing from a building.
Rebels apparently got their hands on various types of arms, ammunition and even gas masks from a military supply barracks in this video:
Residents reportedly have shuttered shops, and gasoline and bread are in short supply. But neighborhoods away from the fighting in the sprawling city still retain some semblance of normalcy, though many people have left.
Video by a BBC crew in Aleppo shows rebels setting up sniper positions in battered buildings, firing on helicopters with a machine gun mounted on a captured tank, and rounding up men, presumably suspected regime collaborators.
The Syrian government said its forces in Aleppo had killed scores of "terrorists," the official term for the armed opposition. The state news service accused insurgents of assaulting citizens and attacking property in the al-Sakhour neighborhood, which also was reportedly under rebel control.
There was no definitive word on casualties. Rebel medics were treating wounded in makeshift clinics, which have sprung up in battle zones across Syria during the uprising.
Insurgents called the attack on Aleppo an all-out offensive that has galvanized dozens of rebel brigades from throughout northern Syria. The fighters are seeking to wrest control of the city and use it as a base to expand their power in the north, where they already have effective control of large swaths of territory.
"Aleppo now is the center of the revolution," said another opposition activist reached on the outskirts of the city. "The liberation of Aleppo means the fall of the regime."
Losing Aleppo would be a major blow to the Assad government, and there was widespread expectation of a concerted government counterattack with fresh reinforcements from northern garrisons.
On Tuesday, U.S. Secretary of State Hillary Rodham Clinton predicted that rebel territorial gains could result in an insurgent "safe haven" inside Syria, presumably in the northern regions. She urged the opposition to start thinking about how to govern.
Neighboring Turkey, fearing a spillover in violence, said Wednesday that it had closed its borders with Syria, at least to commercial traffic.
The once-bustling truck traffic and movement of goods between the two nations has largely ceased because of the raging conflict. Syrian rebels have seized several border posts.
Turkey, once a close ally of Assad, has sided openly with the rebels trying to overthrow him and has provided a refuge for the opposition just across the border.
-- Alexandra Sandels and Patrick J. McDonnell
Photo: Insurgents clash with forces loyal to President Bashar Assad in the center of Syria's restive northern city of Aleppo on Wednesday. Credit: Bulent Kilic / AFP/Getty Images