The Israel Defense Forces said Friday morning that it has struck approximately 450 targets in the Gaza Strip over the past day from the air, sea and ground amid "extensive battles with terrorists."

"The troops continue to operate to locate and destroy underground tunnel shafts, weapons, and additional terror infrastructure," the IDF said in a statement.

During operations in Gaza’s southern city of Khan Yunis, Israeli ground troops directed fighter jets "to kill numerous terrorists in a two-hour series of precise strikes," according to the IDF.

Overnight, Israeli warships "used precise ammunition to strike dozens of terror infrastructure sites used by the Hamas naval forces in the central and southern Gaza Strip," the IDF said.

-ABC News' Dana Savir and Morgan Winsor

The remains of an Israeli citizen thought to be kidnapped by the militant group Hamas were identified overnight, ABC News has learned.

The Israeli Prime Minister's Office announced Friday morning that the number of hostages currently held captive by Hamas in the Gaza Strip is 137, down from 138.

Be'eri, a kibbutz in southern Israel near the border with Gaza, confirmed Friday morning the death of one of its residents, Dror Kaplun, who was initially believed to be a hostage but was actually killed in the Oct. 7 terror attack. His wife, Dr. Marcel Freilich Kaplun, was also killed in the attack, according to the kibbutz.

-ABC News' Anna Brund, Jordana Miller and Morgan Winsor

Photos and video circulating online Thursday show dozens of Palestinian men being detained by the Israeli military, many stripped down to their underwear, in the streets of a city in northern Gaza.

In one of the images, dozens of men are lined up against a wall while kneeling with their hands behind their backs and stripped down to their underwear. The same image shows dozens of other men in an Israel Defense Forces truck. ABC News geolocated a sign for a pharmacy captured in the image to the city of Beit Lahia in northern Gaza.

A video of the same scene shows a long line of men in their underwear sitting and standing in a line, surrounded by IDF personnel.

When asked about the images and video, the IDF told ABC News that its troops "apprehended hundreds of terror suspects" in Shejaiya, Jabalya and Khan Yunis.

Hamas said in a statement in response to the images that the men were unarmed civilians.

Hani Almadhoun, director of philanthropy for the United Nations Relief and Works Agency, told ABC News that several of his family members were detained by the IDF, including his 72-year-old father, brother and 13-year-old nephew.

"They just want the job to feed to provide for their families to make a buck here and there live in a nicer home. That's all not happening now for them," he said. "Now they've been dubbed as operatives and combatants when they were napping in their homes in the safety of their homes with their kids."

Almadhoun, who is based in D.C., said he hasn’t heard from them since and doesn't know how to go about finding information on their whereabouts.

-ABC News' Emmanuelle Saliba, Kerem Inal, Layla Ferris, Helena Skinner and Victoria Beaule

A senior Hamas official in Lebanon warned Thursday that the chances of another hostage release are "dwindling" and that the detainees will not be returned until "the aggression stops."

"The chances of their return diminish with the length of the aggression, and their impact may be lost forever," the official, Osama Hamdan, said in a statement. "The possibilities of their return are dwindling as the aggression goes on and maybe there will be no trace of them forever."

Nearly 140 hostages are believed to still be held by Hamas, according to the Israel Defense Forces.

"Civil order is breaking down in Gaza" and "society is on the brink of full-blown collapse," warned Thomas White, director of UNRWA affairs in Gaza.

"The streets feel wild, particularly after dark," White wrote Friday on X, the social media platform formerly known as Twitter.

He said some aid convoys have been looted and some U.N. vehicles were stoned.

With Gaza under "constant bombardment" and food and supplies limited, the "UNRWA’s ability to assist and protect people is reducing fast," Philippe Lazzarini, commissioner-general of the UNRWA, said in a letter to the president of the U.N. General Assembly.

“In my 35 years of work in complex emergencies, I would never have expected to write such a letter, predicting the killing of my staff and the collapse of the mandate I am expected to fulfill," Lazzarini said. "I urge all member states to take immediate actions to implement an immediate humanitarian cease-fire, enforce international law including the protection of civilians, U.N. staff, U.N. premises including shelters, medical facilities and all civilian infrastructure and protect the prospects for a political solution vital to peace and stability and the rights for Palestinians, Israelis, the region and beyond."