A Syrian warplane flattened a three-storey building, suspected rebels detonated a deadly car bomb and both sides traded gunfire in hotspots across the country, leaving a United Nations-backed holiday truce in tatters on its second day.
The unravelling of the ceasefire marked the latest setback to ending Syria's civil war through diplomacy. Foreign military intervention is unlikely, raising the grim prospect of a drawn-out war of attrition between President Bashar Assad and those trying to topple him.
The proposed four-day truce during the Muslim holiday of Eid al-Adha had been a long shot from the start since international mediator Lakhdar Brahimi failed to get solid commitments from all combatants.
Fighting dropped off in the first hours of the ceasefire on Friday, but by the end of the day, activists said 151 people had been killed in bombings and shootings, a standard daily toll in Syria.
On Saturday, the first regime air strike since the start of the truce reduced a three-storey building in the Arbeen suburb of the capital Damascus to rubble, killing at least eight men, said the British-based Syrian Observatory for Human Rights, which compiles reports from activists.
In the remote eastern town of Deir el-Zour, assailants detonated a car bomb near a military police compound, then opened fire at those rushing to the scene, killing a total of eight people and causing extensive damage, the observatory said.
Syrian media denied there were casualties. The attack bore the hallmarks of Jabhat al-Nusra, a radical rebel-allied Islamic group that has rejected the ceasefire.
The Syrian air force also bombed rebel positions on Saturday during a fierce battle for control over the main road linking Aleppo, Syria's largest city, with the capital, activists said.
Earlier this month, rebels seized Maaret al-Numan, a town along the highway and besieged a nearby military base, disrupting regime supplies to embattled Aleppo. The Syrian air force has responded with sustained bombing raids on area villages.
By Saturday night, at least 76 people had been killed across Syria, including 20 soldiers, activists said. The observatory reported deadly regime shelling and sniper attacks in several locations, while Syrian state-media said rebels ambushed a number of military positions.