Over the past four weeks the world has watched a humanitarian tragedy unfold in Gaza. For UN staff like me it has been particularly tough. Nine of our schools have been attacked, 11 of my colleagues have been killed. They include Ahmed Mohamed Mohamed Ahmed, a school principal, Inas Shaban Derbas, a 30 year-old teacher and the youngest, Abdallah Naser Khalil Fahajan, who at 21 was a school attendant. UN chief, secretary-general Ban Ki-moon called the most recent attack on Sunday, which took place next to a boys' prep school in Rafah and led to nine deaths including that of a colleague: "a moral outrage and a criminal act."