text:  Striking U.N. facilities is prohibited under international law. But Israel argues that Hamas's use of those facilities also violates international law and makes them a legitimate target. Meanwhile, hundreds of thousands of Palestinians are caught in the middle, trying desperately to find shelter. Last week, an Israeli airstrike hit next to a U.N. school in the city of Khan Yunis. Ahmed Akramzakzouk was staying in the schoolyard with his children. I was there before. Someone came to warn me.