A United Nations humanitarian aid convoy inside Syria was hit by airstrikes, UN officials said, as the Syrian military declared that the week-long US-Russian brokered ceasefire had failed.
With the truce apparently teetering on the brink of collapse, the US said it's prepared to extend the agreement, and Russia - after blaming rebels for the violations - suggested it could still be salvaged.
UN officials said the UN and Red Crescent convoy was delivering assistance for 78,000 people in the town of Uram al-Kubra, west of Aleppo city.
Initial estimates indicate that at least 18 of the 31 trucks in the convoy were hit, as well as the Red Crescent warehouse in the area.
The Britain-based Syrian Observatory for Human Rights said at least 12 were killed in the attack, mostly truck drivers and Red Crescent workers.
Jan Egeland, humanitarian aid coordinator in the office of the UN envoy for Syria, told AP in a text message that the convoy was "bombarded".The Syrian Civil Defense, the volunteer first responder group also known as the White Helmets, confirmed that casualty figure.
Egeland added, "It is outrageous that it was hit while offloading at warehouses."
UN Humanitarian Chief Stephen O'Brien called on "all parties to the conflict, once again, to take all necessary measures to protect humanitarian actors, civilians, and civilian infrastructure as required by international humanitarian law".
The convoy, part of a routine interagency dispatch operated by the Syrian Red Crescent, was hit in rural western Aleppo province.
The White Helmets first responder group posted images of a number of vehicles on fire in the dead of the night.
A video of the attack showed huge balls of fire in a pitch black area, as ambulances arrive on the scene.
Devastating news: @SYRedCrescent attacked in rural #Aleppo. We're shocked humanitarian workers have again suffered the brutality of conflict
A Red Crescent official in Syria confirmed the attack, but said no further information was available.
Elsewhere at least 20 civilians were killed in fresh airstrikes on rebel-held Aleppo city and the surrounding areas, according to the Observatory.
And Russia said government positions in southwestern Aleppo came under attack from militant groups, including a massive barrage of rockets.
With the week old ceasefire in danger of unraveling, both Moscow and Washington have indicated a desire to try and salvage the agreement - which had brought a brief respite to at least some parts the war-torn country.
In the wake of the Syrian military declaration, US Secretary of State John Kerry acknowledged that the first stage of the truce - which called for a week of calm and the delivery of humanitarian aid to several besieged communities - had never really come to fruition.