Nine U.S. citizens have been killed in the fighting between Hamas and Israel, a State Department spokesman said Monday, the third day of fighting since Hamas’s attack on Israel began. Israel announced a full siege of the Gaza Strip, with Defense Minister Yoav Gallant saying there would be “no electricity, no food, no fuel.” Earlier Monday, Hamas said it struck the Israeli cities of Jerusalem, Tel Aviv, Sderot, Ashkelon and Ashdod with rockets; later in the day, the Israel Defense Forces said they intercepted militants crossing into Israel from Lebanon.