The deal, mediated by the United States, offered a glimmer of hope in a conflict that has taken an immense human toll.

The dispute underscores the fragility of the deal as mediators worked to ensure that it would go into effect on schedule.

Israel intensified strikes on Gaza hours after a ceasefire and hostage release deal was announced, residents and authorities in the Palestinian enclave said, as mediators sought to quell fighting ahead of the truce's start on Sunday.