The story that Denzel posted from Human Rights Watch is quite interesting actually. Says that both sides are in violation, blah blah blah. And this quote:
"At the same time, Israel should not target individuals and institutions in Gaza solely because they are part of the Hamas-run political authority, including ordinary police. Only attacks on military targets are permissible, and only in a manner that minimizes civilian casualties."
And this:"Israel must not make a blanket decision that all police and police stations are by definition legitimate military targets," Stork said. "It depends upon whether those police play a role in fighting against Israel, or whether a particular police station is used to store weapons or for some other military purpose."
In Gaza, since there is no actually military, no army, navy, etc, who is fighting the Israelis? Is there a difference between a policeman and a militiaman? I don't have the answer to that.
Also according to the article, militiamen can gather and plan attacks inside a mosque, but Israel can't attack a mosque unless there are weapons inside.