In this Monday photo, a Palestinian girl sits on the wall of the New Gaza United Nations School, where dozens of families have sought refuge after fleeing their home in fear of Israeli airstrikes.

Resting in his father's lap after fleeing Israeli airstrikes, Bilal Attar, 4, now shares a classroom in the New Gaza Boys United Nations school in the Gaza Strip with more than a dozen people. The Associated Press

Palestinian girl Fulla Attar, 10, rests in a classroom of the New Gaza Boys United Nations school, where dozens of families have sought refuge after fleeing their home in fear of Israeli airstrikes. The Associated Press

sisters Mariam Attar, center right, and Sada Attar, center left, rest with their children inside the New Gaza Boys United Nations School after fleeing their home in fear of Israeli airstrikes in Gaza City. The Associated Press

Commissioner-General Pierre Krahenbuhl, of the United Nations Relief and Works Agency for Palestine Refugees in the Near East, surveys the New Gaza Boys United Nations School, where dozens of families have sought refuge after fleeing their home in fear of Israeli airstrikes. The Associated Press

A Palestinian family displaced by ongoing violence clean a classroom where they now live in the New Gaza United Nations School, where dozens of families have sought refuge after fleeing their homes in fear of Israeli airstrikes. The Associated Press

Displaced Palestinians fill empty bottles of water at the New Gaza Boys United Nations School, where dozens of families have sought refuge after fleeing their home in fear of Israeli airstrikes. Families sought shelter in the same U.N. school where they stayed during the previous two rounds of fighting. The Associated Press

Resting in his father's lap after fleeing Israeli airstrikes, Bilal Attar, 4, now shares a classroom in the New Gaza Boys United Nations School in the Gaza Strip with more than a dozen people. The Associated Press

A boy cools off on a hot summer day at the Gaza Boys United Nations School, where dozens of families have sought refuge after fleeing their home in fear of Israeli airstrikes. The Associated Press

Palestinian children wait for the bodies of Sarah Omar el-Eid, 4, her father Omar, 26, and her uncle Jihad, 27, to be brought in a house during their funeral in Rafah, southern Gaza Strip. The Associated Press