"The preparation for these convoys has now resumed and we are ready to deliver aid to besieged and hard-to-reach areas as soon as possible," the UN's humanitarian office (OCHA) said in a statement.
The Monday attacks came as relief supplies intended for desperate Syrian civilians were being unloaded at the warehouse Orum al-Kubra, a town in Aleppo province.
Those killed included volunteers as well as a Syrian Arab Red Crescent (SARC) staffer.
The Syrian Observatory for Human Rights, a monitor group, said the attack was the result of air strikes, which if confirmed, would strongly implicate Russian or Syrian aircraft as neither opposition nor jihadist groups have air power.
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An unnamed US official told AFP that Washington believed a Russian plane was responsible.
Both Moscow and Damascus have denied involvement.
Boosting aid deliveries has become a top UN priority in Syria, with convoys repeatedly blocked for security reasons, refusals by the Syrian government to grant authorisation and strict conditions imposed by opposition groups.