Any child death is tragic, but this is really one of the most targeted strikes in the history of warfare. It is safe to believe that everyone that was given a pager for secret communication by a terrorist group, is associated with such group, probably in a military capacity. Furthermore, videos show that extremely close bystanders are left unhurt.
I think this only goes out to show that criticism towards Israel waging warfare is not really about the way that warfare is fought, but really on the right of Israel to fight at all. As no one in history has achieved a more precise attack in urban setting towards a non-uniformed organization ever.