Syrian or Russian warplanes bombed aid trucks near Aleppo late on Monday after a fragile week-long ceasefire ended, the Syrian Observatory for Human Rights reported.
Air strikes hit aid trucks near Aleppo - monitors and resident
The Syrian army could not immediately be reached for comment.
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It said the trucks had made a routine aid delivery organised by an international organisation to an area west of Aleppo city, and had been hit near the town of Urm al-Kubra.
A local resident told Reuters by phone that the trucks had been hit by around five missiles while parked in a centre belonging to the Syrian Red Crescent in Urm al-Kubra. The head of the centre and several others were badly injured, they said.
The aid convoys had been arriving regularly from Turkey and their contents were mostly supplied by various regional and international charities.
The United Nations had said earlier on Monday that aid including wheat flour and health supplies for 78,000 people was to be delivered to Urm al-Kubra.
The United Nations and Red Cross said they were investigating the reports.
The Observatory reported 35 strikes in and around Aleppo since the truce ended.
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