Answer

In my opinion, there is no permission whatsoever to do such a thing, assuming it is known that hostages are there. One does not save a person at the cost of another person’s life, even if many people are involved. All the more so here, where there is no tangible and concrete danger, only an estimate of a general risk. If this bombing is necessary on the strategic level (that is what is needed to eliminate Hamas and there is no other option, not even one that would cost soldiers’ lives), then there may perhaps be room to permit it, though even there I have very great doubt.
Something similar can be said about releasing terrorists in the Shalit deal. They saved one person’s life at the price of risking many other lives. But the risk was general and not concrete, so it is hard to compare one against the other. If releasing the terrorists had been a direct threat to the lives of specific Israelis, then clearly it would have been forbidden to make the deal. Nothing I have said should be taken to imply that the deal was correct or worthwhile. My claim is only that from the standpoint of Jewish law there is no prohibition; that is a matter of policy.