In a surprise announcement, a top Hamas leader says the militant group will release six living Israeli hostages on Saturday and the bodies of four others on Thursday, including the remains of the Bibas family, who for many Israelis have embodied the captives’ plight in Gaza.

Israel has said it is gravely concerned about Shiri Bibas and her two young sons, Ariel and Kfir, but has not confirmed their deaths. Hamas said they were killed in an Israeli airstrike early in the war.

Kfir, who was 9 months old at the time, was the youngest hostage taken in Hamas’ Oct. 7, 2023, attack that triggered the war. A video of the abduction showed Shiri swaddling her redheaded boys in a blanket and being whisked away by armed men.

Hamas leader Khalil al-Hayya, in prerecorded remarks on Tuesday, said the “Bibas family” would be included in the handover of four bodies – the first to be released under the current ceasefire.

The six to be released on Saturday are the last living hostages to be freed under the ceasefire’s first phase. Three had been expected to be freed.

It was not immediately clear why Hamas had changed the plan. But an Israeli official, speaking on condition of anonymity in line with regulations, said Prime Minister Benjamin Netanyahu had agreed to allow long-requested mobile homes and construction equipment into Gaza as part of efforts to accelerate the hostages’ release.

Hamas last week threatened to hold up the release of hostages, citing the refusal to allow in mobile homes and heavy equipment among other alleged violations of the truce.

The hostage releases have come in exchange for hundreds of Palestinian prisoners held by Israel.

The ceasefire that began in mid-January has paused the deadliest fighting ever between Israel and Hamas, surged aid into devastated Gaza and allowed hundreds of thousands of Palestinians to return to their homes as Israeli forces withdrew from much of the territory.

The sides have yet to negotiate the second and more difficult phase, in which Hamas would release dozens more hostages in exchange for a lasting ceasefire and an Israeli withdrawal.

Major challenges are ahead. Israel’s government says it wants to eliminate Hamas’ military and governing capabilities in Gaza. But the militant group quickly reasserted its control of the territory during the ceasefire despite losing leaders and many fighters.

In addition, U.S. President Donald Trump’s new proposal to relocate the Palestinians out of Gaza so the U.S. can redevelop the territory has been rejected by the Arab world and by the Palestinians, who fear they’ll never be allowed to return. But Israel has embraced the plan, and it and the Trump administration have emphasized they share the same goals in the war.

Israelis were horrified by the sight of three emaciated hostages in an earlier release this month, and revelations about hostages being held alone, barefoot or in chains have increased the pressure on Netanyahu’s government to push ahead with the ceasefire’s next stage.

Families and others fear that time is running out — and the news about the Bibas family confirmed that once again.