At least 40 civilians were killed Friday and hundreds more injured when Syrian regime and Russian warplanes struck a crowded market in Eastern Ghouta, an opposition-held Damascus suburb.
Turkish-backed rebels have seized the centre of Afrin city in northern Syria, Ankara said on Sunday, as they made rapid gains in their campaign against Kurdish forces.
A Britain-based war monitor, the Syrian Observatory for Human Rights, said clashes continued inside the city.
An exodus of similar proportions was under way hundreds of kilometres (miles) to the north in the city of Afrin, where Kurdish forces have been almost encircled by Turkish troops.
Turkish government spokesperson and Deputy Prime Minister Bekir Bozdağ said the military campaign would continue to secure areas around Afrin and make sure food and medicine were available.
"We will take all necessary steps to bring the people of the region living in our country or other places back to their homes as soon as possible", he said.
Russian Federation hits back by throwing out 23 British diplomats
There's no evidence at this stage that his death and the attack on the Skripals are linked, it said. Putin's spokesman Dmitry Peskov says Johnson's claims violated all rules of diplomatic protocol.
He added Turkish special forces had been deployed in the city.
Along with Eastern Ghouta, the Kurdish-held town is now among the worsening flashpoints, as the conflict in Syria enters its eighth year.
The new push by the government squeezes rebels in a small corner of the eastern suburbs of Damascus known as eastern Ghouta.
Oways al-Shami, a spokesman for the Syrian Civil Defense, said the airstrikes targeted a market and a nearby residential area where scores of people had gathered to buy bread and vegetables during a daily truce called by Russian Federation.
Syria internal war has killed more than 3,50,000 people and displaced several millions since it broke out in 2011 with the brutal repression of anti-government protests.
Turkey considers the YPG to be a "terrorist" group and the Syrian offshoot of the Kurdistan Workers' Party (PKK) which has waged a bloody three-decade insurgency against the Turkish state.
Airstrikes in Syria killed more than 100 people on Friday as civilians fled en masse. Other videos and photos shared by the Turkish-backed FSA fighters on social media showed them in residential streets, making victory signs and waving flags.
"There was fierce fighting throughout the night on the northern outskirts of the city as the Turkish forces and their Syrian allies tried to break into the city", the Observatory said.