The strike prompted a reaction of visceral anger from the international community, with officials from the UN and US saying they were "disgusted" and "outraged."
The UN estimates that 18 of 31 trucks in the aid convoy were hit. A Syrian Arab Red Crescent warehouse was also hit, the UN said.
The Syrian Civil Defense, a volunteer EMS service, posted video of the aftermath of the attack on social media.
The regime has not claimed responsibility for the airstrikes.
Twelve people involved in the aid delivery were killed, according to the Syrian Observatory for Human Rights, a UK-based organization that monitors the conflict in Syria.
At least 32 people in total were killed in strikes that hit Aleppo and its western suburbs, SOHR said.
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| People walk near Castello road (background) in Aleppo, Syria, September 14, 2016. Photo: Reuters |
The violence comes just hours after Syrian authorities declared that a fragile ceasefire in the war-torn country is over.
UN and US officials strongly condemned the incident.
"Our outrage at this attack is enormous," said Staffan de Mistura, the UN's special representative for Syria. "The convoy was the outcome of long process of permission and preparations to assist isolated civilians."
Stephen O'Brien, the head of the UN's relief organization, said he was "disgusted" by the reports and said if it's discovered that aid workers were deliberately targeted, that the strike would amount to a war crime.
The State Department also said it was outraged by the reports: "The destination of this convoy was known to the Syrian regime and the Russian federation and yet these aid workers were killed in their attempt to provide relief to the Syrian people."
Before news of the attack broke, neither the US nor Russia -- the countries which brokered the ceasefire -- publicly said that the ceasefire is over.
