As some 40,000 residents fled, Russian military police were deployed in the town.
A chemical attack on a rebel-held town in eastern Ghouta was said to have killed at least 49.
'Help is getting fainter' in besieged Syrian region.
No food, no medical supplies, no light, no air. The besieged Syrian city has become a living hell.
Two different offensives in recent days have prompted an exodus of thousands of civilians.
The convoy of 25 aid trucks is carrying around 340 tonnes of food.
“When the international community consistently fails to act, there are times when states are compelled to take their own action.”
Government authorities are preventing surgical kits, insulin, dialysis equipment and other supplies from reaching the enclave of 400,000 people.
In Syria's Ghouta region, attacks continue even after a United Nations ceasefire.
The onslaught has been one of the fiercest of the civil war, now entering its eighth year.