30 Injured in Gaza Attack During Humanitarian Cease-Fire

The strike happened at Al-Shata Refugee Camp in west Gaza City, ABC News has learned. That’s far from Rafah, in southern Gaza, which has been the scene of particularly heavy fighting and strikes the past few days.

Israel’s self-declared truce – which Hamas has not agreed to – does not include areas where its soldiers were already operating.

Israel has been drawing down its ground operation since the weekend but has kept up heavy aerial, offshore and artillery bombardments of the strip. The Gaza war, now in its fourth week, has left more than 1,800 Palestinians and more than 60 Israelis dead.

United Nations officials say more than three-quarters of the dead in the war have been civilians, including the 10 people killed Sunday at a U.N. school that has been converted into a shelter in the southern Gaza Strip town of Rafah. U.N. Secretary-General Ban Ki-moon called the attack a "moral outrage and a criminal act" and demanded a quick investigation, while the U.S. State Department condemned the strike in unusually strong language.

"The United States is appalled by today's disgraceful shelling outside an UNRWA school in Rafah sheltering some 3,000 displaced persons," State Department spokeswoman Jen Psaki said.

"The suspicion that militants are operating nearby does not justify strikes that put at risk the lives of so many innocent civilians," her written statement read.

Israel launched its military operation in Gaza on July 8 in response to weeks of heavy rocket fire and has since carried out more than 4,600 airstrikes across the crowded seaside territory. It sent in ground forces on July 17 in what it said was a mission to destroy the tunnels used by Hamas to carry out attacks inside Israel.

Since the fighting erupted, Hamas has fired more than 3,200 rockets into Israel, many of them intercepted by Israel's Iron Dome defense system.

The number of children killed during the current military operation, at least 392, has surpassed the number of children killed during Israel's "Cast Lead" military operation in 2008 and 2009, UNICEF said.