BEIRUT: Islamic State (IS) group jihadists have released hundreds of civilians they used as human shields while fleeing a crumbling stronghold in northern Syria, but the fate of others remained unknown on Saturday. On another front, scores of civilians were killed on Saturday in air raids by the Syrian regime and its Russian ally, and in shelling attacks by the rebels in the battleground province of Aleppo, a monitoring group said. At least 51 civilians including four children were killed in Aleppo City and the surrounding countryside, while another 22 civilians were killed in the neighboring province of Idlib, the Syrian Observatory for Human Rights said. The last remaining IS fighters abandoned the city of Manbij near the Turkish border on Friday after a rout the Pentagon said showed the extremists were “on the ropes.” The retreat from the city, which IS captured in 2014, was the jihadists’ worst defeat yet at the hands of the Syrian Democratic Forces (SDF), an Arab-Kurdish alliance backed by US air power. Fleeing fighters took around 2,000 civilians, including women and children, on Friday to ward off air strikes as they headed towards the IS-held frontier town of Jarabulus, according to the SDF.