Fifteen children and two women were killed in an air strike on a school in Syria’s Eastern Ghouta late on Monday, a Britain-based monitor said.
The Syrian Observatory for Human Rights said the bombing raid hit Arbin, a key town in the dwindling rebel-held enclave of Ghouta that has been under attack by forces loyal to Syrian President Bashar Al Assad for more than a month.
"Three missiles from a single air strike hit the school, where the underground level was being used as a shelter," Rami Abdel Rahman, who heads the monitor, told AFP.
"Rescue workers are still searching for survivors.”
The Observatory — which identifies air strikes based on flight patterns, munitions used and aircraft — said Russia was suspected to have carried out the raid.
Moscow has said it is helping the Assad regime “finish off” fighters in Ghouta but has denied carrying out strikes against civilians.
On Tuesday, the Russian foreign ministry said that 79,702 civilians, most of whom are children, have evacuated from Eastern Ghouta since the start of a humanitarian mission.
It said in a statement posted on its website that on Monday, 6,046 civilians left the district via humanitarian corridors.
Since February 18, Syrian troops and allied militia have been waging a ferocious ground and air assault to flush out rebels from Ghouta, just east of the capital Damascus.
They have captured more than 80 per cent of the former opposition and have splintered the remaining territory into three sections, each held by a separate rebel group.
The pocket where Arbin lies is held by the Faylaq Al Rahman faction.
Syrian troops have made sweeping advances against them in recent days, opening a "corridor" for civilians to flee into government-controlled territory.
Other residents have opted to flee deeper into the shrinking rebel-held areas.
The White Helmets rescue force, which works to extract people out from the rubble after air strikes, said on Monday its teams in Arbin were responding to a strike on a "basement" there.