@DarkGamer that's a bit of a misconception. They're not legal targets according to most international law experts. Eg

Even when civilian housing may be used by combatants to take shelter, as alleged in the attacks on the Jabalia refugee camp, launching attacks on entire apartment blocks is prohibited if they will lead to disproportionate damage, death and displacement of a large number of civilians, the UN expert warned.

“No asserted right of self-defence under international law can cover such attacks,” he said. “This is particularly the case when the right of self-defence is asserted in the context of an occupation.”

Source