Strikes by Syrian army missiles on an area northeast of the capital Damascus killed at least fifty people on Saturday, rescue workers said.
They said more bodies were believed to be under the rubble of buildings occupied by dozens of families in the city of Douma, about 15 km (10 miles) northeast of Damascus, with dozens of victims taken to field hospitals, many seriously wounded.
Rescue workers said 20 bodies were identified. A further 32 victims remained unidentified and the toll was expected to rise as civil defense workers step up the search amid the rubble of the four multi-storey buildings that were directly hit.
“There are entire families still under the rubble. We couldn't reach them yet, because as you know the process of removing debris must be done with extreme caution," said Majd, an official from the Syrian civil defense corps, a group which operates in rebel-held areas.
The latest casualties follow last Sunday's air strike on a bustling market place in the same area which killed at least 100 people.
Rebels shell main prison
Sunday's attack on Douma was one of the bloodiest in the four-year-long war that has killed an estimated quarter of a million people and driven 10 million from their homes. The conflict grew out of protests against President Bashar al-Assad in 2011 which were put down with brutal force.
The UK-based Observatory for Human Rights said the heavily populated parts of the area where at least 250,000 civilians lived were probably hit by ground to ground missiles on Saturday, followed by air raids.
A United Nations commission of inquiry into the Syrian war has previously accused the government of indiscriminate shelling and aerial bombardment, including the use of barrel bombs regularly dropped on crowded areas.
The Syrian army denies it targets civilian areas and said it strikes at hideouts of armed insurgents who seek to topple Assad.
Meanwhile, Syria's Interior Ministry says insurgents have shelled the central prison near the capital, killing at least 10 and wounding more than 40.
The Interior Ministry statement carried by state TV did not say if the dead and wounded included prisoners from the jail known as Adra Prison, just northeast of Damascus. The statement did not say which specific group was responsible for the attack.
Rebels have shelled Damascus on several occasions over the past weeks, killing and wounding dozens of people.