Damaged buildings in the old city of Homs
President Bashar al-Assad's forces renewed a ground and aerial bombardment of Aleppo on Friday, extending efforts to crush rebels in Syria's commercial capital in what the United States said it feared could become a massacre.
Insurgents targeted army roadblocks and security installations, with both sides avoiding close-quarters warfare in the city of 2.5 million people, Syria's biggest urban centre, reports Reuters.
The U.S. State Department said credible reports of tank columns moving on Aleppo, along with air strikes by helicopters and fixed-wing aircraft, represented a serious escalation of Assad's efforts to crush a rebellion that began 16 months ago.
"This is the concern: that we will see a massacre in Aleppo, and that's what the regime appears to be lining up for," State Department spokeswoman Victoria Nuland said.
Troops stationed on the outskirts of Aleppo unleashed barrages of heavy-calibre mortar rounds on the western neighbourhoods of Saladin, al-Sukkari and al-Fardos, while Russian MI-25 helicopter gunships struck al-Sakhour in the east with rockets, several opposition activists in the city said.
In the first reported casualty on Friday, a man of about 60 wearing a traditional white prayer outfit was killed near a park in Saladin. His body was placed in a mosque pending identification.
Thirty-four people were killed in Aleppo and its environs on Thursday, according to opposition activists keeping a tally of casualties in the northern city.
"The rebels have so far been nimble, and civilians have mostly been the victims of the bombardment," said activist Abu Mohammad al-Halabi, speaking by phone from the city.
"There is lots of internal displacement, and schools have been turned to makeshift shelters that are packed. One shell hitting a school will result in a catastrophe," he said.
"The regime is massing troops and tanks at the entrances of Aleppo, but it seems it is for now content with bombarding the city, with the rebels constantly on the move."