At least 20 people, including seven women and a child, were killed in an aerial bombardment on Saturday of Al-Bab in Syria's Aleppo province, an NGO said.
Regime helicopters dropped explosive-laden barrels on the town in the northern province causing widespread damage, the Syrian Observatory for Human Rights said.
Footage posted by activists on YouTube showed chaos in the aftermath of the attack.
Clouds of dusts and smoke hung in the air, and rubble from surrounding buildings was strewn on the streets and across vehicles.
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Two men tried to open the door of a red pick-up truck that had been completely mangled by the blast, its ceiling caved in and an apparently dead man lying across the front seats.
Another man lay on the ground, still astride his tipped-over motorbike, with his head in a pool of blood.
A third man, seated in the front of a truck, was slumped against the window, with an apparently fatal head wound visible.
The Syrian regime has regularly been accused by the opposition, foreign governments and rights groups of using so-called "barrel bombs" against civilians.
The US State Department has described the weapons as "incendiary bombs which contain flammable material that can be like napalm."
Al-Bab, in northeastern Aleppo, has regularly been targeted by air strikes, including one on a field hospital in September that killed 11 people, according to the Observatory.