KHAN YOUNIS, Gaza Strip — Hamas was preparing to release more than a dozen hostages Saturday for several dozen Palestinian Arab prisoners held by Israel, part of an exchange on the second day of a cease-fire that has allowed critical supplies into the Gaza Strip and given civilians their first respite after seven weeks of war.

While uncertainty remained around the details of the exchange, there was optimism, too, amid the scenes of joyous families reuniting on both sides. 

On the first day of the four-day cease-fire, Hamas released 24 of the about 240 hostages taken during its October 7 attack on Israel that triggered the war, and Israel freed 39 Palestinian Arabs from prison. Those freed in Gaza were 13 Israelis, 10 Thais and a Filipino.

On Saturday, Hamas provided mediators Egypt and Qatar with a list of 14 hostages to be released, and the list has been passed along to Israel, according to an Egyptian official speaking on condition of anonymity because he was not permitted to talk about details of the ongoing negotiations. A second Egyptian official, also speaking on condition of anonymity, confirmed the details.

Under the truce agreement, Hamas is due to release one Israeli hostage for every three prisoners freed. Israel’s Prison Service said earlier Saturday it was preparing 42 prisoners for release. It was not immediately clear how many non-Israeli captives may also be released.

Overall, Hamas is to release at least 50 Israeli hostages, and Israel 150 Palestinian Arab prisoners, during the four-day truce, all women and minors. Israel has said the truce could be extended an extra day for every additional 10 hostages freed — something President Biden said he hoped would occur.

Separately, a Qatari delegation arrived in Israel on Saturday to coordinate with parties on the ground and “ensure the deal continues to move smoothly,” according to a diplomat briefed on the visit. The diplomat spoke on condition of anonymity because he was not authorized to discuss details with the media.

The start of the truce Friday morning paused the Israeli airstrikes on Hamas targets in Gaza. Rocket fire from Gaza militants into Israel went silent as well.

The United Nations said the pause enabled it to scale up the delivery of food, water, and medicine to the largest volume since the resumption of convoys on October 21. It was also able to deliver 34,078 gallons of fuel — just over 10 percent of the daily pre-war volume — as well as cooking gas, a first since the war began.

For the first time in over a month, goods reached northern Gaza, the focus of Israel’s ground offensive. The Palestinian Red Crescent said 61 trucks carrying food, water and medical supplies headed there on Saturday, the largest such convoy to reach the area since the start of the war.

The UN said it and the Palestinian Red Crescent were also able to evacuate 40 patients and family members from a hospital in Gaza City, where much of the fighting has taken place, to a hospital in Khan Younis.

The relief brought by the cease-fire has been tempered, however, for both sides. For Israelis, by the fact that not all hostages will be freed. For Palestinians, by the brevity of the pause.

The freed Israelis included nine women and four children 9 and under. They were taken to Israeli hospitals for observation and were declared to be in good condition.

At a plaza dubbed “Hostages Square” in Tel Aviv, a crowd of Israelis celebrated the good news but pressed for more. “Don’t forget the others because it’s getting harder, harder, and harder. It’s heartbreaking,” said a Tel Aviv resident, Neri Gershon.

Israeli leaders have said they would resume fighting eventually and not stop until Hamas, which has controlled Gaza for the past 16 years, is crushed. Israeli officials have argued that only military pressure can bring the hostages home. Yet the government is under pressure from hostages’ families to make the release of the remaining captives the top priority.