The attack on the Jisr al-Haj neighbourhood yesterday killed at least 28 people and wounded nearly 30, the Britain-based Syrian Observatory for Human Rights said.
It said the count may rise because many wounded are in critical condition.
The Local Coordination Committees, another monitoring group, said some 50 people were believed killed in the attack.
It provided the names of only 13, saying the bodies were hard to identify.
Both groups are based abroad and rely on an activist networks in Syria. The Aleppo Media Center, based in the city, said over 40 people were killed. Differing casualty figures are not uncommon.
The Aleppo Media Center posted an online video that purportedly showed rescue workers extinguish fire-engulfed buses as civilians scrambled to untangle bits of cars and motorcycles from the dead.
Aleppo, once Syria’s largest city, is a major battleground in the country’s civil war, carved into rebel- and government-held neighbourhoods. Insurgents mostly control the countryside.
Earlier this month, Amnesty International sharply condemned the government’s reliance on barrel bombs, saying they killed over 3,000 civilians in Aleppo last year.
Meanwhile yesterday, international aid group Handicap International warned Syria is so awash with weapons and bombs that the 5.1 million people living there, including 2 million children, are at constant risk. It called on all parties in the conflict to abide by international humanitarian law and immediately end the use of explosives in highly populated areas.
Syria’s conflict, now in its fifth year, has killed more than 220,000 people. At least 1 million have been wounded.
Underlining the danger civilians face, two explosive- rigged motorcycles blew up in the central city of Homs, killing at least four people and wounding 28, Syrian state media said.
The Islamic State group claimed responsibility, saying it targeted neighbourhoods home to members of President Bashar Assad’s minority Alawite sect.
(AGENCIES)