Islamic State has claimed responsibility for suicide and car bomb blasts that struck a Damascus suburb near Syria's holiest Shi'ite Muslim shrine, and a monitoring group said at least 20 people were killed.
State television showed debris, mangled cars and wrecked shops in a main commercial thoroughfare near the Sayeda Zeinab shrine, in an area where at least three bomb attacks claimed by Islamic State have killed and wounded scores of people this year.
The ultra-hardline Sunni militants of IS, whose many foes are advancing on a number of fronts in both Syria and Iraq, are avowed enemies of Shi'ites, whom they consider a heretical group within Islam.
State media said at least eight people were killed in Saturday's blasts.
But the UK-based Syrian Observatory for Human Rights said the death toll had risen to at least 20, including at least 13 civilians, with the other victims coming from pro-government militias.
It said the number was expected to rise because many of the scores of wounded people were in critical condition.
Islamic State, also known as Daesh, said two of its suicide bombers had blown themselves up and operatives had detonated an explosives-laden car, according to the IS-affiliated Amaq news agency.
US State Department spokesman John Kirby said Washington condemned the attack in the strongest terms.
"This terrorist act demonstrates once again the inhumanity and brutality of all that Daesh does and all it stands for," he said.
The Sayeda Zeinab shrine is a magnet for thousands of Iraqi and Afghan Shi'ite militia recruits who go there before being assigned to front lines, where they fight against the Sunni rebel groups trying to topple President Bashar al-Assad.
The heavily garrisoned area near the shrine is also a well known stronghold of Lebanon's powerful Shi'ite Hezbollah group, an Iranian-backed movement that is one of Assad's chief allies.