Strike a civilian center. Strike the EMS workers that respond to the attack. Strike anyone who responds to aid the EMS workers.
Eventually, what you've killed isn't simply other humans. What you've killed is the popular supply of social empathy. You've engaged in a kind of natural selection, by which anyone with a reflexively decent and caring bone in their body is wiped from the face of the Earth.
This is how you destroy a civilization. This is how you make the rest of the Middle East more Israeli.