The most powerful Syrian rebel faction on the fringes of Damascus has begun abandoning its stronghold in the once rebel-held enclave of eastern Ghouta.
The move sets the stage for the final chapter of the government's relentless offensive to fully retake the area after seven years of revolt.
The first fighters from the Army of Islam left the town of Douma in the morning hours of Monday as part of an evacuation deal that will hand the town to the Syrian government, the state SANA news agency reported.
The rebels were heading to Jarablus, a town in northern Syria where control of the territory is shared between Syrian rebels and Turkish forces.
The Syrian government dispatched more than 50 buses to Douma to take the rebels out, SANA reported. By midday, only a handful had left for the north in three buses.
There was no immediate comment from the Army of Islam.
The Britain-based Syrian Observatory for Human Rights, which monitors the civil war through a network of activists on the ground, also reported the evacuation.
Rami Abdurrahman, the observatory's director, said some factions within the Army of Islam oppose evacuating and effectively surrendering Douma to the government of President Bashar Assad.
The deal over Douma would mark the end of a weeks-long push by Assad's forces to consolidate their control over eastern Ghouta, just outside the capital.
Douma was one of the earliest centres of the anti-government demonstrations that swept through the country in March 2011.
Syrian government forces responded by putting the town and other suburbs around Damascus under siege, bombing hospitals and residential areas, and blocking the entry of food and medical relief.
Local activists have said that more than 100,000 civilians were trapped inside Douma, which suffered devastating damage.
The most recent Syrian air and ground offensive on eastern Ghouta, supported by Russia's military, has killed at least 1,600 people, according to the observatory.
More than 120,000 others have fled their homes and sought safety with the government, according to Russia's military operation in Syria.
Russia is a key backer of Assad.
Over the past weeks, as Syrian forces reclaimed towns and villages in eastern Ghouta, they gave rebels and all men of fighting age the choice of accepting amnesty and serving in the Syrian military conscription, or leaving to go to the north of Syria.
Thousands chose the north, taking with them their families.
More than 40,000 Syrian rebels and their family members have relocated to rebel-held north Syria, according to the Russian military.
Turkey, with support from rebels, is running its own military operations against a US-backed Kurdish militia in northern Syria, which controls territory along the frontier.
On Sunday, the Syrian government-linked Central Military Media outlet said that once the evacuations are completed, a local council for Douma will be formed with the approval of the central government.