The 20-day war has killed more than 1,030 Palestinians, mainly civilians. Israel has lost two civilians. More than 160,000 displaced Palestinians have sought shelter at dozens of U.N. schools, an eight-fold increase since the start of Israel's ground operation more than a week ago, the U.N. said.

Three Israeli tank shells hit the school in the town of Beit Hanoun on Thursday, killing 16 people and wounding scores. The school served as a shelter for Palestinians displaced by the Gaza fighting.

Israeli airstrikes have destroyed hundreds of homes, including close to 500 in direct hits. Entire Gaza neighborhoods near the border have been reduced to rubble.