LONDON — American-Israeli hostage Edan Alexander, who had been held captive by Hamas in Gaza since Oct. 7, 2023, was released on Monday after successful negotiations between the U.S. and the Palestinian group.

Alexander’s mother, Yael, has arrived at Re’im military base in Israel near the Gaza border to see her son before he’s taken to a hospital in Tel Aviv. Retired Brig. Gen. Gal Hirsch, the Israeli coordinator for prisoners of war and missing persons, and U.S. Middle East envoy Steve Witkoff are also heading to the military base, an Israeli official told ABC News.

Israeli security officials told ABC News there would be a temporary pause in combat, airstrikes and aerial reconnaissance in the area of Gaza where 21-year-old Alexander was to be released. The pause will last until Alexander crosses into Israeli territory, officials said, which is expected to take less than 30 minutes.

Alexander, a New Jersey native, traveled to Israel at the age of 18. He was serving in the Israel Defense Forces when captured from his base close to the Gaza frontier during Hamas’ Oct. 7 attack. He was 19 when abducted and has had two birthdays while in captivity.

Alexander is the last living American citizen still believed to be held hostage by Hamas. The terror group is believed to also be holding the bodies of four dead American hostages, according to U.S. officials.

Israeli Prime Minister Benjamin Netanyahu on Monday met with Witkoff and U.S. Ambassador to Israel Mike Huckabee, per a readout from his office. Netanyahu also spoke with President Donald Trump, the statement said, with the Israeli leader thanking Trump for his assistance in securing Alexander’s release.

“The prime minister discussed the last-ditch effort to implement the outline for the release of the hostages presented by Witkoff, before the escalation of the fighting,” the statement said. “To this end, the prime minister instructed that a negotiating delegation be sent to Doha tomorrow.”

“The prime minister clarified that the negotiations will only take place under fire,” it added.

Hamas announced its intention to free Alexander on Sunday, describing the decision as a “part of the steps being taken to achieve a ceasefire.”

The statement said Hamas has been in contact with American officials “over the past few days” as part of ceasefire negotiations.

Trump posted to Truth Social saying Alexander’s release “is the first of those final steps necessary to end this brutal conflict.”

A U.S. official familiar with the deal to release Alexander told ABC News that the agreement came together in recent days via direct talks between the U.S. and Hamas.

Alexander’s release is being viewed as a goodwill gesture toward the Trump administration and a potential opening to jumpstart talks surrounding the broader conflict, U.S. officials told ABC News.

Still, officials said the U.S. did not secure all the concessions it was seeking. Negotiators had also been pushing Hamas for the release of the remains of the four dead American hostages still held in Gaza, officials said.

Alexander’s family said in a statement released through the Hostage Families Forum that it was informed of Hamas’ announcement and “is in continuous contact with the U.S. government regarding the possibility of Edan’s expected release in the coming days.”

They added that “it is forbidden to leave any hostage behind” and said that “Israel is committed to ensure the return of all 58 remaining hostages without delay.”

Alexander was one of the 253 hostages taken during Hamas’ Oct. 7 attack, in which some 1,200 people were also killed, according to Israel.

Israel’s subsequent offensive in Gaza had killed 52,829 people and wounded 119,554 more as of Sunday, according to figures released by the Hamas-run Ministry of Health in the strip.

This is a developing story. Please check back for updates.

ABC News’ Shannon K. Kingston contributed to this report.