BEIRUT >> Hundreds more civilians fled what remained of the Syrian opposition’s enclave in Aleppo on Saturday as rebels and government forces exchanged artillery and mortar fire across the northern city.

In central Syria, reports circulated that a government warplane crashed while flying raids against the Islamic State group near the historic city of Palmyra.

The group’s Aamaq news agency claimed its militants downed the jet near the Jazal oil fields west of the city.

Syrian government forces backed by the Russian military recaptured Palmyra and its famed ancient Roman ruins from the IS group in March this year. The two militaries have since turned their attention to fighting local opposition forces in Aleppo and Damascus.

The Britain-based Syrian Observatory for Human Rights said a government jet crashed in the Jazal area. It reported IS militants were attacking government positions 2.5 miles from Palmyra, which the government recaptured from the extremists to great fanfare in March. The activist-run Palmyra Coordination Committee said the jet was a MiG-23.

The Observatory said Friday that the IS assault near Palmyra has killed at least 49 pro-government forces.

The Syrian government did not comment on the reports.

The Observatory reported heavy clashes in Aleppo’s southern neighborhoods, but rebels appeared to have held their ground on Saturday after two weeks of advances by government forces and allied militias nearly erased them from the city.

Syrian state media said nine civilians were killed in retaliatory rebel shelling on government-held areas of the city. The Observatory reported 24 civilians were killed in the past 24 hours.

Opposition activists accused the government of dropping bombs laden with poisonous chlorine gas on the Kalaseh neighborhood, one of the few still held in the city by the opposition, in the early hours Saturday.

Wissam Zarqa, an English teacher trapped inside the government’s siege, said he could still smell chlorine around midday.

State television station al-Ikhbaria showed footage of hundreds of people carrying children and belongings crossing on foot to the city’s government-held areas, where they were being received by state social workers and security services personnel.

The U.N.’s humanitarian response agency OCHA reported Saturday that the government was confiscating IDs to vet the people seeking refuge. The agency expressed concerns about the vetting process. The U.N. human rights office has expressed concern about reports that hundreds of men have disappeared after crossing from eastern Aleppo into government-controlled areas.

State media and other outlets loyal to the Syrian government are pushing to show a return to normalcy for Aleppo, delivering on President Bashar Assad’s promise throughout the six-year war to return to the status quo ante.

Lebanon’s Al-Manar TV channel aired interviews with displaced Aleppo residents it said were arriving from around the country to inspect their homes in the city’s formerly opposition-held neighborhoods. Interviewees praised the military’s advances and sang chants in support of Assad. Al-Manar is run by the militant group Hezbollah, which is fighting alongside government forces in Aleppo.

But some of those who have already returned to see their homes at the sight of looting and the damage wrought on the city’s formerly rebel-held eastern neighborhoods.

The government’s push, preceded by months of air strikes that destroyed schools, hospitals, and first responder centers, has laid waste to the city’s eastern neighborhoods, which have been held by the opposition since 2012.

Russia’s Defense Ministry, which is supporting Syrian government operations in Aleppo, said some 50,000 civilians had fled eastern Aleppo over the past two days in a “constant stream.”

Such figures are impossible to verify. The Observatory said “hundreds” have fled in recent days but over 80,000 have been displaced over the past two weeks. The U.N. estimates the tally at over 30,000.

Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said the Russian military was providing civilians who have left eastern Aleppo with temporary accommodation, hot meals and medical assistance.

U.S. Secretary of State John Kerry and European and Arab diplomats are meeting members of Syria’s opposition in Paris on Saturday. Kerry said he is working to ensure their safety and to save Aleppo “from being absolutely, completely destroyed.”

U.S. and Russian military experts and diplomats are meeting in Geneva on Saturday to work out details of the rebels’ exit from eastern Aleppo.