The United Nations Secretary-General Ban Ki-moon strongly condemned Israel's Sunday's strike on a UN school as a "moral outrage and a criminal act".
The school in Rafah in southern Gaza was sheltering 3,000 displaced persons and Mr Ban said the "Israel Defense Forces have been repeatedly informed of the location of these sites."
"This madness must stop," he said.
The school in Rafah is the second that has been hit in less than a week.
Also the U.S. declared Sunday it is 'appalled' by Israel's 'disgraceful' attack on the United Nations school sheltering displaced people in southern Gaza.
The statement released by the U.S. State Department noted that the school had been designated a protected location.
"The coordinates of the school, like all UN facilities in Gaza, have been repeatedly communicated to the Israel Defense Forces," State Department spokeswoman Jen Psaki said.