The Syrian regime on Sunday conducted several airstrikes near Damascus, killing at least 100 people and wounding hundreds more, AFP reported.
The Syrian Observatory for Human Rights said four air raids struck a marketplace in the rebel-held town of Douma, adding that the death toll was likely to rise.
"The preliminary information suggests most of the dead are civilians," Observatory Direct Rami Abdel-Rahman said.
Abdel-Rahman said residents rushed to the center of Douma after the first airstrike to help evacuate the victims when more raids struck.
The attacks come as UN humanitarian chief Stephen O'Brien, who took the post in May, made his first trip to Syria.
Douma, in the rebel stronghold of Eastern Ghouta, has been a common target for government airstrikes. Amnesty International has accused President Bashar al-Assad of war crimes conducted in the area.
