The attacks carried out by the Assad regime and its supporters in Eastern Ghouta have killed 674 civilians in the past 12 days, according to a civil defense group Friday.
In a report, the White Helmets said the toll is for regime attacks carried out between Feb. 19 and Friday.
Eastern Ghouta has been under siege for the last five years; humanitarian access to the area, which is home to 400,000 people, has been completely cut off.
In the past eight months, Assad regime forces have intensified their siege of Eastern Ghouta, making it nearly impossible for food or medicine to get into the district and leaving thousands of patients in need of treatment.
Syria has been locked in a devastating conflict since early 2011 when the regime cracked down on demonstrators with unexpected ferocity.
According to UN officials, hundreds of thousands of people have been killed in the conflict to date.