DEIR AL-BALAH, Gaza Strip (AP) — The tense cease-fire between Israel and Hamas appears to be back on track after the release of a second group of militant-held hostages and Palestinian prisoners. But an hourslong delay underscored its fragility. Hamas had accused Israel of violating the agreement, which has brought the first significant pause in seven weeks of war. Israel appeared set to resume its devastating air war and ground offensive until Qatar and Egypt, which mediate with Hamas, announced late Saturday that the obstacles had been overcome. The militants released 17 hostages, including 13 Israelis, while Israel freed 39 Palestinian prisoners. The release of a third group of hostages and prisoners is expected later Sunday. Hamas also said one of its top commanders had been killed, without saying when or how.