BEIRUT -- France struck a compromise Sunday with Russia on a U.N. resolution that it said would prevent “mass atrocities” in besieged areas of Aleppo, where thousands of trapped civilians and rebel fighters await evacuation in freezing temperatures.

On the ground, prospects for swift evacuations from Aleppo and other besieged areas were thrown into doubt again Sunday after militants burned buses assigned to the rescue operation that has taken center stage in the five-year-old Syrian civil war.

The Aleppo evacuations were to have been part of a wider deal that would simultaneously allow more than 2,000 sick and wounded people to leave two pro-government villages that have been besieged by Syrian rebels. Most villagers are Shiite Muslims, while most rebels are Sunni Muslims.

Six buses that were among those poised to enter the villages of Foua and Kfarya on Sunday were set on fire by unidentified militants, presumably to scuttle any deal.

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A video posted online showed armed men near the burning buses as celebratory gunshots rang out. “The buses that came to evacuate the apostates have been burned,” the narrator of the video said. He warned that no “Shiite pigs” would be allowed to leave the towns.

The video could not be verified independently, but was in line with AP reporting from the area.

Earlier Sunday, pro-Syrian government TV stations showed dozens of buses on stand-by at a crossing near eastern Aleppo, reportedly poised to resume evacuations from the opposition’s last foothold in the city.

The evacuations had been suspended two days earlier amid mutual recriminations after several thousand people had been ferried out of the war zone. Thousands more desperate civilians are believed trapped in the city.

About 2,700 children were evacuated in the first rescue mission earlier this week, but hundreds more “are now waiting in freezing temperatures, close to the front lines,” said Shushan Mebrahtu of the U.N. agency for children, UNICEF. “We are deeply worried.”

Wissam Zarqa, an English teacher and Aleppo resident, said he went to an evacuation point on Sunday afternoon and found buses with evacuees on board, but that the vehicles did not move. The opposition’s Britain-based Syrian Observatory for Human Rights also said the buses hadn’t left the city.

A bus convoy with Aleppo evacuees was stuck for hours in a buffer zone between the front lines in the city, without food or water, according to aid officials familiar with the negotiations between the two sides.

Eastern Aleppo resident Rami Zien, who said he was on one of the buses “stuck in a no-man’s land” between government and rebel control, told The Associated Press via messenger service that evacuees were stressed and frightened. “Government forces are just ahead of me and if anything goes wrong I’ll be the first to die,” he wrote.

Zien said evacuees were crammed 70 people to a bus, with many having no room to sit. He said the Red Crescent, which is facilitating the evacuation, had been unable to provide water. He said there were 50 to 60 buses in the convoy.

On Friday, a bus convoy carrying evacuees was stuck in government territory in Aleppo and was turned back after being searched.

The continued suspension of evacuations is throwing into disarray an Aleppo deal that had been brokered last week by Syria ally Russia and opposition supporter Turkey.

The deal marked a turning point in the country’s civil war. With the opposition leaving Aleppo, Syrian President Bashar Assad has effectively reasserted his control over Syria’s five largest cities and its Mediterranean coast nearly six years after a national movement to unseat him took hold.

After hours of negotiation between Russia, the U.S. and France on Sunday, the U.N. Security Council forged a compromise which, if approved, will allow the U.N. to send monitors to oversee the evacuation of civilians and fighters and ensure their protection if they decide to stay in war-torn Aleppo.

The Council decided to hold the vote on the measure for Monday morning, to allow member states time to consult with their capitals on the details of the deal.

If the compromise vote passes on Monday, there are still hurdles for civilians trying to escape the dire conditions in what was the city’s last rebel enclave, in eastern Aleppo, but CBS News’ Pamela Falk reports it would at least illustrate some level of compromise between Moscow, Washington, and Paris over how to protect civilians in Syria.

France’s U.N. ambassador, Francois Delattre, told reporters the compromise was reached after more than three hours of closed consultations on Sunday and the Security Council would vote on the resolution at 9 a.m. EST on Monday.

He said some countries want to report to their capitals overnight. He said he hoped for a positive vote, but that he remained cautious.

Russia’s U.N. ambassador, Vitaly Churkin, told reporters before consultations that Moscow could not accept the French draft resolution unless it was changed. He presented council members with a rival text.

After the consultations, Churkin said a “good text” had been formulated.

The compromise resolution, which CBS News has seen, asks the Secretary General to take urgent steps to make security arrangements in consultation with interested parties for the evacuations and for the “safe, immediate and unimpeded access of U.N. monitors.”

It “demands that all parties allow complete, immediate, unconditional, safe and unhindered access for the United Nations and its implementing partners, in order to ensure that humanitarian assistance reaches people through the most direct route in order to meet basic needs, including the provision of medical care... for the whole of Syria and respect and protect all civilians across Aleppo and throughout Syria.”

Delattre said approval of the resolution “would give us collectively the tools to avoid... a situation in which, after the end of major military operations, forces including militias, would commit mass atrocities.”

He said the resolution could also offer leverage to negotiate a broader cease-fire “and toward political negotiations.”