The death toll from airstrikes in the Deir al-Asafir district southeast of Damascus has risen to more than 30, mostly women and children, according to the Syrian Observatory for Human Rights and the White Helmet civil
The strikes on Thursday, which the Observatory monitoring group said were carried out by Syrian aircraft, came despite a month-long "cessation of hostilities" in Syria between government forces and their opponents, excluding Islamic State and al-Qaida's Nusra Front.
Airstrikes continued in the area on Friday. Two strikes hit the outskirts of Deir al-Asafir and at least seven hit the village of Bala, just north of Deir al-Asafir, the Observatory said.
The U.S. State Department said it was appalled by the reported airstrikes.
"We condemn in the strongest terms any such attacks directed at civilians," spokesman John Kirby said.
France condemned the attack on Friday and said it violated the truce.
"This abject act is designed to terrorize the Syrian people and sap efforts by the international community to find a political solution," French Foreign Ministry spokesman Romain Nadal said.
Parts of the Eastern Ghouta region east of Damascus, where Deir al-Asafir is situated, have been outside President Bashar al-Assad's control almost since the start of the uprising which erupted five years ago and descended into civil war.
The area is controlled by different factions, including rebel forces covered by the truce, such as Jaish al-Islam, as well as Nusra Front.
The Observatory said 12 children, nine women, a teacher and an emergency response worker were among the 33 dead in Deir al-Asafir.
The "White Helmet" volunteer rescue organization said emergency worker Walid Ghourani was killed when one of its ambulances was hit. It put the death toll at 32.
It released video footage of an ambulance arriving at Deir al-Asafir and a white-helmeted rescue worker, carrying a stretcher over his shoulder, rushing through a rubble-strewn alleyway towards what appeared to be the site of an explosion. It also published pictures it said showed the destruction of the White Helmet base in Deir al-Asafir, including a fuel depot. Fire hoses and gas canisters could be seen among the mounds of collapsed concrete.
The Observatory said Syrian government forces have been trying to surround Deir al-Asafir, which it said is still home to 2,700 families.