CAIRO — The cease-fire between Hamas and Israel will go into effect Sunday at 8:30 a.m. local time, mediator Qatar announced Saturday, as families of hostages held in Gaza braced for news of loved ones, Palestinians prepared to receive freed detainees, and humanitarian groups rushed to set up a surge of aid.

Benjamin Netanyahu has warned he reserves the right to restart the war in Gaza with the backing of the United States if he is not satisfied with Hamas’ handling of the ceasefire deal.It came after he said Israel will not proceed with the ceasefire until he receives a list of the 33 hostages who will be released by Hamas in the first phase.

The UN secretary-general has reacted after Israel and Hamas agreed to have a ceasefire deal to halt the war in Gaza. The conflict had lasted several months.