This sort of thing happens in combat all the time. You've got scared young kids, who probably haven't slept in days, mistakes are going to happen. Sure, maybe they're trigger-happy, and maybe they just want to kill SOMEBODY, but my guess is this is just a tragic accident. And who knows if Hamas isn't using all sorts of ruses, like pretending to surrender, just to get close enough to mount a human kamikazi attack. "Fool me once, shame on you...". You know how that goes. Remember, these are the people who invented the suicide bomber and follow a religion that lionizes "martyrs". And many Palestinians speak Hebrew.

Could it actually be a bloodthirsty killer behind the trigger who was just dying to kill somebody, anybody? Sure, war brings out the worst in people. But if I had to guess, its just a tragic accident. War is chaos, most of the deaths are probably accidental. The gunner rarely sees his target in modern urban combat.