First, I'm a bit doubtful of a news source where they highlight an article called "Ten reasons not to move to Canada". Is there any other source? What time of the day it was, for example?
Second, I'm sorry for the girl and all, it's a horrible thing, et cetera, but what if the bag had in fact contained explosives? Cases of children being used for suicide bombings are not unknown, and it was a "no entry zone" - meaning she shouldn't be there, so at least part of the responsibility is with her parents for letting her go there. If I was the garrison's commander, and had orders to shoot anyone who crossed the perimeter, I'd follow them - unless they had provisions for not engaging a specific type of intruder.
Third, I'm sure all the palestinians are horrified for this, but they don't even blink when Israeli children, alongside their whole families, are killed on suicide bombings of buses and restaurants - places that don't even have the "no entry zone" status.
So yeah, forgive me if I'm not for lynching or hanging that guy. I'd have to hang a lot more people higher on the list before I got to him.