Six workers for the U.N. agency for Palestinian refugees were killed Wednesday when two airstrikes hit a school and its surroundings in a central Gaza refugee camp, the agency said, adding that it was the “highest death toll among our staff in a single incident.” The Israeli military said it was targeting Hamas militants at the Nuseirat camp. In a statement Thursday, the U.N. Relief and Works Agency, or UNRWA, said those killed in the strikes on the camp included the shelter’s manager. About 12...