Syrian regime forces are entered the town of Hammouriyeh on Wednesday as part of the government's ongoing push to reclaim the rebel-held Ghouta enclave.
The battle has become one of the bloodiest of the war, with opposition fighters increasingly besieged.
On Tuesday a group of sick and injured civilians left eastern Ghouta under the first medical evacuation since the offensive began in February.
A 25-truck convoy carrying food and medical aid is scheduled to enter Douma on Thursday
The UN says 400,000 civilians are trapped in eastern Ghouta with little food or medicine. It has called for the urgent evacuation of 1,000 people for medical reasons.