Simple if neither Hamas of Fatah were responsible and it happened in "THEIR" territory all they (Those "governing" the Arabs of Palestine) have to do is find those responsible and bring them to justice or hand them over for the Israelis to try. Or would that not be in their interest? Ask the Taliban, they were given a similar proposition and turned it down - they've bitterly regretted it ever since and so have their Pakistani ISI "Masters". Hamas had best batten down the hatches, retribution is on the way as sure as night follows day, hopefully it will be in the form of targeted strikes over a protracted period, as that will induce them to keep their heads down and prevent them from instigating any more instances of unprovoked attacks against a civil population.