TEL AVIV — Hamas freed six hostages in the latest exchange Saturday, even as heightened tension between the adversaries clouded the future of the fragile ceasefire deal. The exchange completed the first phase of a deal to trade hostages for a ceasefire.

The six included three Israeli men seized from the Nova music festival and another abducted while visiting his family in southern Israel when Hamas stormed across the border in the October 7, 2023, terrorist attacks that triggered Israel’s nearly 16-month campaign in the Gaza Strip.

Two of the hostages had been held by Hamas for around a decade since they each entered Gaza on their own.

Five of the captives were handed over in staged ceremonies that the Red Cross and Israel have condemned in the past — brought out by masked, armed Hamas fighters in front of hundreds of Palestinians before being transferred to Red Cross vehicles.

In the central town of Nuseirat, Omer Wenkert, Omer Shem Tov, and Eliya Cohen were posed alongside Hamas fighters on the stage. A beaming Mr. Shem Tov even kissed two militants next to him on the head and blew kisses to the crowd. 

Hamas has been condemned for such public displays, with Israel, the United Nations, and the Red Cross saying they are cruel and do not respect the dignity of the hostages.

Watching the release, Mr. Cohen’s family and friends in Israel chanted “Eliya! Eliya! Eliya!” and cheered when they saw him for the first time. Mr. Shem Tov’s grandmother ululated in joy, shrieking, “Omer, my joy! My life!” as she saw him.

The Israeli military said the final hostage, Hisham Al-Sayed, 36, was released later Saturday. The Bedouin Israeli crossed on his own into Gaza in 2015 and had been held since. His family has told the Israeli press that Mr. Al-Sayed was previously diagnosed with schizophrenia.

The latest releases, to be followed by the freeing of hundreds of Palestinian Arabs imprisoned by Israel, went ahead after tensions mounted over a grisly and heart-wrenching dispute triggered this week when Hamas initially handed over the wrong body for an Israeli mother of two young boys abducted by the militants, Shiri Bibas.

The remains that Hamas transferred with her sons’ bodies on Thursday were later determined to be those of an unidentified Palestinian woman. In response, Prime Minister Netanyahu vowed revenge for “a cruel and malicious violation,” while Hamas suggested it had been a mistake.

On Friday night, the small militant group believed to have been holding Bibas and her sons — the Palestinian Mujahedeen Brigades — handed over a second body. Bibas’ family said Israeli forensic authorities had confirmed the remains were hers.

“For 16 months we sought certainty, and now that it’s here, it brings no comfort, though we hope it marks the beginning of closure,” the family said.

Difficult negotiations are likely ahead over the ceasefire’s next phase. The ceasefire deal has paused the war but is nearing the end of its first phase. Negotiations over a second phase, in which Hamas would release dozens more hostages in exchange for a lasting ceasefire and an Israeli withdrawal, are likely to be even more difficult.

The six hostages being freed Saturday are the last living ones to be released under the first phase. Messrs. Cohen, Shem Tov, and Wenkert, all in their 20s, were abducted by Hamas terrorists at the Nova music festival. During their release, they were brought out wearing fake army uniforms, though they were not soldiers when they were kidnapped.

Earlier Saturday, two other hostages — Tal Shoham, 40, and Avera Mengistu, 38 — were freed in the southern Gaza city of Rafah. Arriving back in Israel, both were taken to medical centers for examination.

“This is an unforgettable moment, where all emotions are rapidly mixing together. Our Tal is with us,” Mr. Shoham’s family said in a statement, calling for a deal to free all those still captive. “There is a window of opportunity; we must not miss it.”

Israel is to release today 620 imprisoned Palestinians. They include 151 who were serving life or other sentences, around 100 of whom will be deported to other countries, according to the Palestinian prisoners press office. 

They also include 445 men as well as 18 children between the ages of 15 and 17, five aged between 18 and 19, and a woman, all of whom were seized by Israeli troops in Gaza during the current war, according to the press office.

Hamas has said it will also release four more bodies next week, completing the first phase of the ceasefire. If that plan is carried out, Hamas would retain about 60 hostages, about half of whom are believed to be alive.

Hamas has said it won’t release the remaining captives without a lasting ceasefire and a full Israeli withdrawal. Mr. Netanyahu, with the backing of the Trump administration, says he’s committed to destroying Hamas’ military and governing capacities and returning all the hostages.