An operation to evacuate a rebel-held enclave in the Syrian city of Aleppo is now under way, Red Cross officials say.
The ICRC is bringing out 200 wounded people. A fleet of ambulances and buses was also seen heading into eastern areas as part of a wider evacuation.
Fighters and civilians had been due to leave on Wednesday, but an earlier ceasefire collapsed.
Government forces took nearly all remaining rebel-held parts of Aleppo this week after a four-year battle.
Syrian state TV said that “4,000 rebels and their families would be evacuated from eastern districts on Thursday”, adding that “all the procedures for their evacuation are ready”.
A statement from the Russian Centre for the Reconciliation of Opposing Sides in Syria, part of Russia’s ministry of defence, said the Syrian authorities had guaranteed the safety of all members of the armed groups who decided to leave Aleppo.
Hezbollah, the Lebanese Shia Muslim movement backing the Syrian government, said there had been “big complications” but that “intensive contacts between the responsible parties… led to re-consolidating a ceasefire to exit armed fighters from eastern districts in the next few hours”.
The rebels confirmed a fresh ceasefire had come into effect at 03:00 GMT and that a new deal had been agreed.
International Committee of the Red Cross (ICRC) Middle East regional director Robert Mardini said its operation was “well under way” and that “our teams are safe and doing all they can on the ground”.
Syrian activists say civilians are now starting to board buses and ambulances.
As operations began, an ambulance service official in eastern Aleppo said that one convoy of ambulances had been shot at, with three people injured.
The White Helmets civil defence group tweeted that one senior volunteer had been shot and injured by a sniper while clearing an evacuation route for ambulances.
Where will civilians, the wounded and rebels be taken?
Russia’s defence ministry has said buses will take the injured, civilians and rebel fighters to the neighbouring province of Idlib, most of which is controlled by a powerful rebel alliance that includes the jihadist group Jabhat Fateh al-Sham.
The buses will reportedly leave Aleppo on the road through the government-controlled south-western district of Ramousseh heading towards the rebel-held town of Khan Touman, about 8km (5 miles) away.
The chief of the Russian military’s General Staff, Gen Valery Gerasimov, told a news briefing: “A humanitarian corridor has been created for the evacuation of militants.
“This corridor is 21km long,” he said, adding, “6km lie across Aleppo’s territories controlled by government troops and another 15km through territories in the hands of illegal armed groups.”
Twenty passenger buses and 10 ambulances were being used for the operation, the general said. Some rebels were using their own vehicles, numbering 100, he said.
The BBC’s Asaf Aboud, in Aleppo, says the government has indicated that the evacuated civilians will be able to choose whether they want to leave or stay in the city.
BBC producer Riam Dalati says ambulances from Syria Charity, carrying seriously wounded people from eastern Aleppo, have now arrived at the Turkish border.
And Al Jazeera reported that a bus with injured residents had arrived in al-Atarib district in the western Aleppo countryside, after passing through Ramousseh.
* How many remain in eastern Aleppo?
It’s believed up to 50,000 people remain.
That is said to include about 4,000 fighters and about 10,000 family members of fighters.
UN envoy Staffan de Mistura says approximately 30% of the fighters are from the jihadist group formerly known as the al-Nusra Front.
Aleppo’s besieged residents have faced weeks of bombardment and chronic food and fuel shortages.
Medical facilities in the city have largely been reduced to rubble, as rebels have been squeezed into ever-smaller areas by a major government offensive, backed by Russian air power.
* Why did the earlier deal fail?
On Wednesday morning, buses and ambulances had been brought to evacuate rebel fighters and their families – only to be turned away shortly afterwards.