How can they leave? They are prisoners, page-57

I hear what you are saying, anyone that says kill them all needs a slap. They should try to minimise civilian deaths and not drop to the same level. The issue is that Hamas sees things differently to the Jews, they want to wipe all of the Jews out. They understand power and strength not dialogue, they have a religious view that sees a enemy that must all die.
There is only one way you deal these people, speak to anyone that has served in these places, they understand fear and strength only, if you let them get strong they will attack you. They even do it between themselves, look at the civil war they had. Do you think since Hamas has come to power they wanted to have a peace deal? No. Instead they want to wipe Israel.
Sadly Israel needs to clear and take steps to allow its troops as much protection as possible as they move in to remove Hamas in the area, its war.
Remember they voted and won a civil war to have Hamas in control, Hamas has promised the people lies and now the people will suffer even more because of Hamas.