At least 19 civilians were killed on Saturday in shelling by forces allied to the Syrian regime against the Damascus suburb of eastern Ghouta.
Syrian activists and a first responder group say shelling and rocket fire targeted the suburb a day after medical evacuations were completed to save the lives of 29 others.
The victims were six children and 13 adults said the Syrian Civil Defense, volunteer rescuers also known as the White Helmets.
The Britain-based Syrian Observatory for Human Rights monitoring group and the local, activist-run Ghouta Media Center reported the same.
On Friday, the Red Cross and Red Crescent completed the evacuation of 29 patients from the besieged suburbs to receive urgent medical care in government hospitals in Damascus.
More than 400 patients on a UN list waiting for evacuations were left behind however.
It took the International Committee of the Red Cross and the Syrian Arab Red Crescent three days to evacuate the patients and their family members from eastern Ghouta suburbs to hospitals just minutes away, underscoring the degree to which authorities have obstructed basic relief work in the war-torn country.
The UN submitted a list of names to the regime six months ago of patients requiring evacuation from the siege because they were suffering from war wounds, kidney failure, and malnutrition.
The UN says around 400,000 people are trapped under the regime’s siege of eastern Ghouta.
In November, UN humanitarian adviser Jan Egeland said the list had reached 494 names, and 12 patients had died waiting for care. The UN's children's agency said more than 100 children require evacuation.
The regime, which has besieged the eastern Ghouta suburbs with varying degrees of severity since 2013 in response to a revolt against Bashar Assad's regime, refused to allow any evacuations until this week.
Food stores and medical supplies have dried up under the blockade.
UN officials have blasted the use of sieges against civilians in Syria as "medieval" and "barbaric."
Amnesty International called the tactic a crime against humanity.