On behalf of the greater good, sacrificing one would be morally superior to sacrificing several. Can I live with the guilt? I don't know, but here's what went through my mind:
Is it morally permissible to kill one innocent person to save the lives of more innocent people? Or you could look at it as—is it morally permissible to sacrifice multiple innocent people for the life of one?
If one weighs the ramifications on a farther scale, saving one versus saving many, it is of course morally superior to choose the latter. Not either of the choices is the best, but I'm sure most would agree that at that moment, saving more would be certainly better than saving fewer. Not counting what may happen in the long run.
However, 'morally permissible' argues in the moral views of the majority. If only seeing consequences of the moment, would the majority be unable to or willing to sacrifice one? Could they take the blame of that one life? Unless the situation gets truly desperate, I'm guessing general human nature would only permit the former. Which is why not everybody can make or understand the decisions their leaders have to make.
Of course killing someone is never ideal and should always be a last resort, but if there is a situation in which someone will definitely be killed, it is important to minimize the loss of life as much as possible. For that reason if one person's death will save the lives of many, and there is no other way to save those lives, the one death is acceptable.
This question is presented in the abstract, but of course one would never
really have the choice in the abstract. Nobody can know for certain that
his or her action to kill one person with the hope of saving many
others will be successful. In a real situation, all anyone can know is
whether or not he will choose to do murder. Do not do evil in the hope that
good will come. Only do your best to do good and refrain from murder.
God alone may choose to save or kill any other people involved.