Russian Federation struck on Friday a new agreement with an opposition faction in Eastern Ghouta to evacuate the wounded, fighters and civilians to the opposition-controlled northwestern province of Idlib in line with talks launched with Jaysh al-Islam to reach a deal in Douma, the last opposition stronghold near Damascus.
Since February 18, a Russian-backed air and ground assault by Syrian troops has brought most of the area under government control, and Damascus is using evacuation deals to clear the last three pockets.
Damascus and its ally Moscow have implemented a "leave or die" strategy with deadly air strikes on the enclave as they look to end six years of opposition control.
Four major rebel groups are now positioned inside Eastern Ghouta, namely the Islam Army, Failaq al-Rahman, Ahrar al-Sham, and the Levant Liberation Committee, known as the al-Qaida-linked Nusra Front.
Failaq al-Rahman said in a statement Friday that the deal will lead to the immediate evacuation of sick and wounded people for treatment and to allow aid to enter the besieged area.
The departure of thousands of fighters and civilians from the southern part of the onetime rebel bastion had been scheduled to start at 9 am (0700 GMT) but by late morning the buses had yet to arrive, an AFP correspondent reported.
Insurgents in one of those pockets - the town of Harasta - began withdrawing in a convoy of buses for opposition territory in northwestern Syria on Thursday.
The White Helmets, a civil defence organisation operating in rebel-held areas, said most of the dead were women and children. According to the agreement, terrorists from the Jabhat al-Nusra group, who fought on the side of Failak Ar-Rahman, will also go to the Idlib province.
The rebels said in a statement Friday that the agreement will allow humanitarian aid and medical care to be delivered to civilians in the area, who have lived through years of occupation and almost nonstop fighting as of late.
Home to some 400,000 civilian residents, Eastern Ghouta has remained under a crippling regime siege for the last five years that has prevented the delivery of badly-needed humanitarian supplies.
Syrian State news agency SANA says over 4,000 left on Friday.
The UK-based war monitor, the Syrian Observatory for Human Rights, said the blast was caused by rebels detonating their arsenal before departing.
It also broadcast live footage of eight Syrian men, who said they had been detained by Faylaq al-Rahman for over a year and were released under the settlement.
Observatory head Rami Abdel Rahman said the buses would go first to Idlib, then may head to Afrin - a flashpoint town recently captured by Turkey and its rebel proxies from Kurdish forces.
The first deal brokered by Russian Federation was reached with the hardline Islamist group Ahrar al-Sham for the town of Harasta.
"We hate the fact that we have to leave Ghouta", said Abu Khaled, a 28-year-old jihadist fighter and Ghouta native.