The United States issued its heaviest condemnation to date of Israel’s offensive in Gaza, referring to a strike on a United Nations school that killed at least 10 people as "horrifying" and "disgraceful,” NBC News reported. The U.S. ambassador to the U.N. issued a statement calling for a probe by Israel into attacks on U.N.-run schools. Meanwhile, a seven-hour cease-fire went into effect on Monday, but Palestinians have accused Israel of breaking the truce by bombing a house in Gaza City. More than 1,800 Palestinians have died during the Gaza war. Sixty-three Israeli soldiers and three civilians have been killed.