Simultaneous car bombings killed more than 50 civilians and left a trail of destruction in a town near Syria's capital, as rebels downed a second military aircraft in as many days.
The explosives-packed cars blew up at daybreak in a pro-regime neighbourhood of the mainly Christian and Druze town of Jaramana, residents, state media and a rights watchdog reported.
The blasts ripped through a central square near a petrol station, one going off as a bomb-laden car was driven against the traffic down a main road lined by many people.
There was a ball of fire at the end of a narrow lane, and the impact of the explosions brought walls down onto cars. Pools of blood and severed body parts were left behind on the streets, said an AFP photographer.
The Syrian Observatory for Human Rights gave a death toll of 54, all civilians. More than 120 other people were wounded, and many residents rushed with them to hospital.
"What do they want from Jaramana? The town brings together people from all over Syria and welcomes everybody," one told AFP.
The foreign ministry in Russia, a longtime ally of Damascus, strongly condemned the bombings as a "terrorist crime."
"We condemn in the strongest terms these new terrorist crimes, which nothing can justify," it said in a statement, adding that the attacks showed "the traditional methods of international terrorist organisations like Al-Qaeda".
Jaramana has now been targeted by four such bomb attacks in three months. It is home to predominantly Christians and Druze, an influential minority whose faith is an offshoot of Shiite Islam.
Sectarian divides are a key factor in Syria's armed rebellion, with many in the Sunni Muslim majority frustrated at more than 40 years of Alawite-dominated rule.
The uprising erupted in March 2011 with peaceful democracy protests. It transformed into an armed insurgency when the government began a bloody crackdown.
The regime of President Bashar al-Assad, himself from the Alawite offshoot of Shiite Islam, insists it is fighting foreign-backed "terrorists".
The failure of international diplomacy has enabled it to press on with its all-out military campaign to crush the rebellion, and the fighting has resulted in more than 40,000 deaths, according to the Observatory.
At least another 31 people - on top of the 54 who died in Jaramana - were killed in violence across Syria on Wednesday (local time), the watchdog said, updating an earlier toll.
Also, a car bomb attack struck the town of Basra al-Sham, in the southwestern province of Daraa, the Observatory said, without providing a precise casualty toll.
"A huge explosion hit the town," said the Observatory. "It was caused by a car bomb attack. The explosion was followed by the sound of clashes. There were reports of casualties."
An AFP correspondent on the Syria-Turkey border, meanwhile, reported that rebel fighters shot down a fighter jet in the embattled northwest.
The aircraft was hit by a missile and crashed at Daret Ezza, said the Observatory, a Britain-based watchdog that relies on a network of activists and medics on the ground.
Witnesses said the rebels later captured one of the pilots.
"Two pilots used parachutes to jump out of the plane after it was hit," a witness told an AFP reporter one kilometre away in Tourmanin. "One of them was taken prisoner."
The rebels were seen carrying him and taunting Assad in YouTube videos.
"This is your airplane, oh Bashar," a man said in one video as fire and smoke rose from the mass of broken metal. "The (rebel) Free Syrian Army has downed it."
It came a day after rebels downed an army helicopter for the first time with a newly acquired ground-to-air missile, in what the Observatory said had the potential to change the balance of military power.
The gunship was on a strafing run near the besieged northwestern base of Sheikh Suleiman, the last garrison in government hands between Syria's second city Aleppo and the Turkish border.
Little more than a week ago, the rebels seized tanks, armoured vehicles, artillery, 120-mm mortars and rocket launchers when they took the government forces' sprawling Base 46, about 12 kilometres west of Aleppo.