The toll from heavy government bombardment of a rebel stronghold outside the Syrian capital rose on Sunday to 34 civilians, including 12 children, a monitoring group said.
The increased toll came as nine people, including civilians, were killed in rocket attacks on a regime-held neighbourhood northeast of Damascus, the Syrian Observatory for Human Rights said.
"There are now 34 civilians that were killed in Saturday's attacks on Douma, among them 12 children and eight women," said Observatory director Rami Abdel Rahman.
Forces loyal to President Bashar al-Assad struck the rebel-held town of Douma with shells and aerial attacks on Saturday.
By late evening that day, the Observatory had said 20 civilians were killed, but that rescuers were still working to find more victims.
"Overnight, they found more victims underneath the rubble, and others who were wounded died," Abdel Rahman said on Sunday.
He said some of the strikes had killed whole families inside their homes.
Local volunteers and civil defence teams worked Sunday morning to locate seven people who were still unaccounted for, the Britain-based Observatory said.
The Douma Coordination Committee, a local activist group, published the names and photos of documented casualties on its Facebook page.
One of the photos showed a toddler, which the group said had been rescued from beneath the rubble but succumbed to his wounds shortly afterwards.
At least 11 air strikes targeted the Eastern Ghouta area, of which Douma is a part, on Sunday. The Observatory said several people had been wounded, but had no further details.
On August 16, a series of regime strikes left more than 117 people -- mostly civilians -- dead in Douma, sparking international condemnation of the Assad regime.
Eastern Ghouta has been under a government siege for nearly two years and is regularly targeted by regime aerial attacks.
Northeast of Damascus, at least nine people were killed in rocket fire outside of the Adra prison, the Observatory said.
Abdel Rahman said some of those killed were civilians, but he had no additional details.
Syria's war, which began in March 2011 with anti-regime protests, has spiralled into a multi-front conflict that has killed more than 240,000 people.