GENEVA — Pro-government forces retaking the eastern neighborhoods of the besieged Syrian city of Aleppo killed at least 82 civilians on Monday, the United Nations estimated, in what one official called “a complete meltdown of humanity.”
Zeid Ra’ad al-Hussein, the United Nations high commissioner for human rights, warned that the blood bath in Aleppo, a once-thriving northern metropolis that is close to falling under the government’s complete control after more than four years of fighting, could spread to other cities where rebels are active.
“What is happening with Aleppo could repeat itself in Douma, in Raqqa, in Idlib,” he said on Tuesday. “We cannot let this continue.”
Also on Tuesday, the French government said it was “deeply concerned” about reports of a chemical attack in the eastern suburbs of the city of Hama a day earlier. The Union of Medical Care and Relief Organizations, an international coalition of humanitarian groups, said the attack had killed at least 93 civilians and wounded 300, but those numbers could not be confirmed independently.
The death toll for eastern Aleppo, recorded in four neighborhoods — Bustan al-Qasr, al-Fardous, al-Kallaseh and al-Saleheen — included 11 women and 13 children, some shot in the streets as they tried to flee the fighting, said Rupert Colville, a spokesman for the United Nations high commissioner for human rights. He cited reports the world body had received from reliable contacts inside and outside the city.
Mr. Colville said pro-government forces had also reportedly entered homes and killed those they found inside, including women and children.
They also shot and killed civilians on Monday in al-Ahrar Square in al-Kallaseh, and in the Bustan al-Qasr neighborhood, he said, adding that an Iraqi militia group had been among the forces involved.
By early Monday evening, opposition groups were estimated to control just a third of a square mile of the city, Mr. Colville said, citing “deeply disturbing reports” of streets filled with bodies that could not be retrieved by residents because of the intensity of the fighting and of the fear of being shot on sight.
Pro-government television channels showed footage of Bustan al-Qasr eerily empty; its residents appeared to have fled, some going to government-controlled areas and others to the shrinking zones still held by rebels.
“Civilians have paid a brutal price during this conflict, and we are filled with the deepest foreboding for those who remain in this last hellish corner of opposition-held eastern Aleppo,” Mr. Colville said.
Jens Laerke, a spokesman for the United Nations office coordinating emergency relief, reported that about 37,000 people had fled eastern Aleppo to western areas of the city or to the surrounding countryside. An estimated 14,700 took refuge in collective shelters, including in a cotton factory, he said. He called the events “a complete meltdown of humanity.”
Foreign Minister Jean-Marc Ayrault of France called the assault on Aleppo a “martyrdom.”
In a statement, he described “coldblooded murders of entire families on the ground who were deemed close to the opposition; summary executions, including of women and children; people burned alive in their homes; the continuation of systematic targeting of hospitals, their staff and their patients.”
He added, “Such atrocities have outraged the conscience.”
Thousands of civilians remain in areas previously held by rebel groups, including opposition activists and civil defense members who Mr. Ayrault said now risked detention, torture and death.
Some rebel fighters escaped, while others surrendered to pro-government troops and were escorted out of the city, Mr. Ayrault added. Russian television showed footage of such scenes.
The United Nations has heard from families outside the conflict area that they had lost touch with relatives inside the city, Mr. Colville said.
Only monitoring by the United Nations or other external bodies would allay the suspicion that widespread crimes may be underway, Mr. Colville said.
The Aleppo Media Center, an activist group of journalists and citizens, reported mass killings of families in eastern Aleppo, but the reports could not be independently confirmed.
Jan Egeland, the United Nations humanitarian adviser for Syria, said the governments of Russia and Syria were “accountable for any and all atrocities that the victorious militias in Aleppo are now committing.”
The International Committee of the Red Cross issued an urgent call for all combatants to put humanitarian objectives ahead of military ones and to reach an agreement on evacuating civilians. “We stand ready to oversee the implementation of any mutual agreement that puts civilians first,” the group’s Syria director, Marianne Gasser, said in a statement from Aleppo. “We cannot urge this strongly enough: This must happen now.”