Civilians and rebel fighters have begun leaving the Syrian town of Darayya after a deal was reached ending a four-year government siege.
The first buses left the town, near the capital Damascus, accompanied by ambulances and Red Crescent vehicles.
But the UN has expressed concern over the plan, saying it is essential that those leaving do so voluntarily.
The Syrian army encircled Darayya in 2012 and just one aid delivery has reached the town since then.
The first bus to emerge from the town carried mostly children, women and elderly people, AFP news agency reports.
Some 700 armed men and 4,000 civilians will be evacuated as part of the agreement, according to Syrian state media.
Opposition fighters are due to be given safe passage to the rebel-held city of Idlib, while civilians will go to government shelters in Damascus.
The office of UN Special Envoy Staffan de Mistura sounded a note of caution saying it was “imperative that people of Darayya are protected in any evacuation that takes place, and that this takes place voluntarily”.
A statement said the UN was neither involved nor consulted about the evacuation plan, but added, “the world is watching.”
For years those living in Darayya have endured constant shelling, as well as suffering shortages of food, water and electricity.
Some of those leaving said the town had become uninhabitable.
Darayya saw some of the first protests against the Syrian government, an uprising that transformed into a full-blown civil conflict.
The withdrawal of rebels just a few miles from Damascus is a boost for President Bashar al-Assad, analysts say.
The evacuation comes as US Secretary of State John Kerry holds talks on Syria with his Russian counterpart Sergei Lavrov in Geneva.
They are meeting in a bid to broker a temporary ceasefire in the city of Aleppo, where fighting between government and rebel forces has escalated in recent weeks, leaving hundreds dead.
Russia’s President Vladimir Putin and Turkish counterpart Recep Tayyip Erdogan have agreed a deal to boost aid to Aleppo, Turkish media reported.
Determined diplomacy: Analysis by Lyse Doucet, BBC News, Geneva
Russian and American teams in Geneva, involving military officials and diplomats, have been able to reach agreement on most details of a possible deal. It is up to John Kerry and Sergei Lavrov to try to close the last difficult gaps. One of the most sensitive issues is said to be the grounding of Syria’s warplanes.
Western sources say senior US defence officials are deeply sceptical, if not resistant, to closer military co-operation with Moscow. But achieving progress in Syria, especially in the battle against so-called Islamic State, is one of the White House’s key goals. So John Kerry continues his determined diplomacy to reach some kind of deal with Russia.
But today’s evacuation in Darayya which involves the surrender of rebel forces, underlines the Syrian government’s long-held view that the road to peace goes through local Syrian deals, largely on its terms.
Syria Darayya: Evacuation of siege town begins