Israel will observe a 12-hour "humanitarian window" in Gaza on Saturday at 1 a.m. ET, a spokesman for the Israeli Defense Forces said Friday on Twitter. Hamas will also observe the 12-hour ceasefire, a spokesman for the group said, according to the Associated Press. An optimistic U.S. Secretary of State John Kerry said Friday that he'll continue peace talks in Paris on Saturday and hopes to achieve a seven-day halt to hostilities in honor of the post-Ramadan festival of Eid, which will likely fall on Monday. Eighteen days of fighting have left 867 Palestinians and 38 Israelis, including 35 soldiers, dead.