Also asked about this, several people from the policeman to a government employee. All agree and present the following explanation:
The president decided , for some unknown reason, to drive on his own in an unmarked car in the desert in a restricted zone. When challenged, by a shot being fired in the air, he did not stop- hence his wounding. Apparently after the incident the president apologised for not respecting the rules of military check points.
Sounds just a little odd but that is what everyone has said.