Instead of battling each other, fighters in the south use weapons abandoned by government forces to take territory.
Activists say a Syrian military air strike has killed at least 14 people and wounded many others in the northern Syrian province of Aleppo after striking a neighbourhood with crude bombs.
The military aircraft dropped at least one “barrel bomb” – crude weapons made from canisters laden with explosives and hurled from helicopters – to strike Kafr Hamra, a suburb in northwest Aleppo city on Tuesday, activists said.
The UK-based Syria Observatory for Human Rights confirmed that several people were killed, including two children and a woman, and that the death toll was likely to rise because more people were buried under the rubble.
At least two dead children were piled onto the back of a flat-bed lorry; at least one was covered under a bright red blanket; a man referred to the children as being torn apart as he partially lifted the blanket, according to a video of the incident uploaded to social media.
Another video of the incident showed a burning vehicle. It was not clear if something else was targeted as well.
The Syrian military widely uses so-called barrel bombs to strike at rebel-held areas.
They have been widely criticised because they cannot be precisely targeted, and are believed to have killed thousands of civilians, particularly in northern Syria.
The Kafr Hamra attack came just hours after 13 people were killed on Monday night in al-Bab, a town also in Aleppo province but controlled by the Islamic State of Iraq and the Levant (ISIL), according to activist sources.
Al Jazeera cannot independently verify the activist accounts due to reporting restrictions inside Syria.
Meanwhile, on a different front, the Syrian Observatory said Syrian Kurds fighting ISIL have made new gains in the town of Kobane, expelling the fighters from several central buildings and seizing weapons.
Tuesday’s advance came just hours after the US-led coalition launched four strikes against ISIL positions in central Kobane, the Syrian Observatory said.
The Kurdish People’s Protection Units (YPG) staged a “special operation” during which they captured six buildings used by ISIL, according to the Syrian Observatory, which relies on a network of sources in Syria.
It said 13 ISIL fighters were killed in the fighting.
The Kurds “captured a large amount of weapons and ammunition, including RPG (rocket-propelled grenade) rounds, light weapons, sniper guns and thousands of heavy machinegun rounds”, the Syrian Observatory said.
The US and Arab allies began strikes against ISIL positions in Syria in late September, just days after the group launched its assault on Kobane.
About 1,200 people, mainly fighters, have been killed in the battle for the town on the border with Turkey.
Kobane has become a major symbol of resistance against ISIL, which has committed widespread atrocities and imposed its harsh interpretation of Islamic law in areas under its control.
YPG fighters are battling alongside Iraqi Peshmerga forces and Syrian rebels that have reinforced the town’s defences, backed by US-led strikes on ISIL positions.
The multi-sided Syrian war has killed more than 195,000 people and forced millions from their homes since it began three and a half years ago as an uprising against President Bashar al-Assad’s regime.