Long answer
Israel did not fire at the aid convoy it was providing security for. The Palestinian Arabs, desperate to get to the food before Hamas takes it as usual, stormed the trucks immediately after they entered Gaza. The Egyptian drivers, fearing for their lives in light of past attacks by Palestinian Arabs, did their best to get away, and in the process ran over the people storming the trucks. Some distance away, other Palestinian Arabs tried to approach Israeli forces, and after refusing to keep their distance the Israeli Army fired warning shots, which had nothing to do with the storming of the aid trucks.
