Hamas freed two hostages and was set to release four more from Gaza on Saturday in exchange for hundreds of Palestinian prisoners and detainees, after Israel confirmed that a body handed over hours earlier was that of hostage Shiri Bibas.

Less than 24 hours after Israel found that remains delivered by Hamas did not belong to Ms. Bibas, a slain Israeli hostage, the militant group said it had returned another body.

Hamas had said Bibas’ remains were returned to Israel with those of her sons, Ariel and Kfir, and another hostage Thursday. Testing confirmed the identities of the three others but found the remains said to be Shiri Bibas were instead those of an unidentified Palestinian woman.