The UN has suspended all aid convoys to Syria after an airstrike hit a 31 truck convoy near Aleppo on Monday.
The UN said the convoy had proper permits and all warring parties – including Russia and the US – had been notified.
Eighteen of the 31 trucks carrying wheat, winter clothes and medical supplies, were hit.
A senior official of the Syrian Arab Red Crescent was among civilians killed.
While it was not clear who carried out the attack, the US said it would raise the issue with Russia.
Aid deliveries to besieged areas were a key part of the cessation of hostilities deal brokered by the US and Russia seven days ago.
US secretary of state John Kerry made the following statement before the attack was carried out.
“The important thing is the Russians need to control Assad, who evidently is indiscriminately bombing, including of humanitarian convoys. So let’s wait and see and collect the facts. We need to see where we are, and then we’ll make a judgment.”
His comments follow reports that the recent ceasefire deal, brokered by the US and Russia, had ended.
Earlier the Syrian military announced in a statement that the effect of that “truce regime” was now at an end.