The delayed evacuation of rebels and their families from eastern Aleppo got off to a rocky start Thursday morning, with the first ambulances believed to be carrying civilians coming under fire, allegedly from pro-government forces.

After that one reported incident, however, the tense evacuation operations appeared to be underway, with Arabic media showing a convoy of green Syrian government buses from eastern Aleppo arriving at al-Rashedeen, the first rebel checkpoint in opposition territory west of Aleppo.

Later Thursday, Russia’s defense ministry said all rebels had been removed from eastern Aleppo, leaving the long-fought-over city completely in under Syrian control. The ministry said at least 3,000 rebels had left their former enclave during the military offensive to bring the city under government control, and Lt. Gen. Viktor Poznikhir of the military’s General Staff told The Associated Press that 1,000 people were evacuated during the cease-fire.

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The figures from Russia’s government could not be independently confirmed, and were not immediately corroborated by the opposition side.

Evacuations from the rebels’ tiny remaining enclave in the east of the massive, largely destroyed city had been set to begin Wednesday morning after a night of truce, but were scuttled by a resumption of violence. Rebels said President Bashar Assad’s army resumed shelling them after the night of calm without provocation, while the regime insisted opposition forces took the first shots.

Either way, it resulted in another day of punishing airstrikes -- including suspected cluster bombs -- on the opposition enclave, where the United Nations estimates some 50,000 civilians could still be trapped.

Early Thursday morning, the evacuations were given the green light from the armed factions on both sides. Hezbollah, a militant Shiite group based in neighboring Lebanon that has fought alongside Assad’s own army, said the flailing cease-fire had been reinstated Thursday, and a Syrian army official told the AP that convoys carrying people out of eastern Aleppo were to start rolling “at any moment.”

But as soon as the first convoy of trucks started rolling, they got hit with small arms fire, according to multiple witnesses and activists on the ground.

In a video posted to YouTube, a member of the Syrian Civil Defense group -- the first responders known colloquially as the White Helmets -- said at least three people were wounded in the attack on the ambulances, including a driver and civilians being transported by the vehicles.

“Regime forces opened fire on us,” the man, who identifies himself as Hassan Haji Ibrahim, says in the video. “Civil defense staff inside the ambulances were injured. Civilians were also injured inside the ambulances. Some are in critical condition.”

Ibrahim said the alleged pro-government forces first fired into the air, causing the evacuation convoy to pull back toward eastern Aleppo, but “more shooting occurred, so we pulled back again. The third time, they aimed straight at us.”

An unverified image posted online by Syrian opposition activists shows two wounded men, allegedly the drivers of vehicles in an evacuation convoy that came under fire from Assad regime-allied forces as it tried to carry rebels and civilians out of eastern Aleppo, Dec. 15, 2016.

Images posted online by anti-government activists showed injured men, purportedly the drivers of vehicles from the convoy.

The convoy of ambulances reported pulled all the way back from the border crossing point into eastern Aleppo.

Without any reference to the shooting incident, Russia’s Ministry of Defense and the International Red Cross both said later Thursday that evacuations were underway.

The Russians said operations to remove about 5,000 people, including rebels and their family members -- had begun, with buses entering eastern Aleppo to ferry them out. Russia’s defense ministry said a second convoy that departed Thursday night was accompanied by Russian military officers.

The buses were to carry the evacuees west out of Aleppo into Idlib province, where they were meant to be released into opposition territory.

Those areas where the rebels and their families were to be evacuated have also been under intense bombardment by Syrian and Russian forces for weeks.

There were no reports of widespread violations of the tenuous cease-fire, and activists and opposition groups did not report any new airstrikes Thursday morning.