Pro-opposition activists uploaded footage of what they half-jokingly called a "fireworks display" over Hammouriyeh. Other images depicted members of the Syrian Civil Defense known as the White Helmets, rescue crews working in opposition-held areas, racing to extinguish burning bodies scattered on the ground.
Rami Abdul Rahman, who heads the Observatory, claimed Thursday that government forces used Thermite munitions, incendiary bombs whose use is banned by the Convention on Certain Conventional Weapons. Russia is among the countries that signed that agreement.
Thursday's violence forced humanitarian groups to postpone the entry of an aid convoy into Duma, the de facto rebel capital in Ghouta.
"We postponed it because there are many developments. ... The situation is rapidly evolving and it's difficult for us to go with the convoy," said Ingy Sedky, the spokeswoman for the International Community of the Red Cross, in a phone conversation Thursday.
Earlier this week, a 46-truck convoy entered the Ghouta and delivered medical supplies as well as food to some 27,500 people. But the shelling, which continued even as aid workers raced to unload their cargo, meant half the supplies remained on the trucks, the U.N.'s coordination office said in a statement Thursday.
The postponement leaves Ghouta's residents in a state of "constant tension and fear," said Pawel Krzysiek, a Red Cross spokesman who was aboard the supply convoy.
"These people basically spent the last two weeks underground in makeshift basement shelters," he said Tuesday. He said as many as three families would crush into a single room to escape the violence, often going without water, basic sanitation and little food.
Thousands have been uprooted in the territory as the constant airstrikes have emptied out entire towns, while so-called humanitarian corridors that are supposed to provide a safety route for people to evacuate were impossible to reach.
Krzysiek said the people in Ghouta he spoke with "don't really care about politics and affiliations and loyalties. They really want this to stop."
"They want this to be over. ... They just said, 'Make the (warring sides) reach any agreement to just stop this hell.'"