The family of Israeli-American hostage Hersh Goldberg-Polin says he has been killed in the Gaza Strip.

The family issued a statement early Sunday, hours after the Israeli army said it had located bodies in Gaza.

"With broken hearts, the Goldberg-Polin family is devastated to announce the death of their beloved son and brother, Hersh," it said.

"The family thanks you all for your love and support and asks for privacy at this time."

The Israeli Defence Forces (IDF) confirmed on Sunday the deaths of Goldberg-Polin and five other hostages — Carmel Gat, Eden Yerushalmi, Alexander Lobanov, Almog Sarusi, and Master Sergeant Ori Danino.

President Joe Biden issued a statement late Saturday night, he was "devastated and outraged" by the news of Goldberg-Polin's death.

"It is as tragic as it is reprehensible," read the statement from President Joe Biden. "Make no mistake, Hamas leaders will pay for these crimes. And we will keep working around the clock for a deal to secure the release of the remaining hostages."

The announcement is certain to put pressure on Prime Minister Benjamin Netanyahu to reach a deal to bring home remaining hostages.

The Israeli leader has said military pressure is needed to win their release as ceasefire efforts falter.

Before Israel's announcement, Israel said it believed 108 hostages were still held in Gaza and about one-third of them were dead.

Hamas-led gunmen killed some 1,200 Israelis and foreigners and abducted around 250 hostages on Oct. 7, according to Israeli tallies.

Since then, Israel's military has levelled Gaza, driving nearly all of its inhabitants from their homes and killing at least 40,000, according to Palestinian health authorities. Israel says it has killed some 17,000 militants.

Goldberg-Polin, 23, was seized by militants at the Nova music festival in southern Israel on Oct. 7.

The native of Berkeley, California, lost part of his left arm to a grenade in the attack.

In April, a Hamas-issued video showed him, his left hand missing and clearly speaking under duress.

The video sparked new protests in Israel urging the government to do more to secure freedom for him and other hostages.

Goldberg-Polin's parents became perhaps the most high-profile relatives of hostages on the international stage.

They met with Biden, Pope Francis and others and addressed the United Nations.

On Aug. 21, they addressed a hushed hall at the Democratic National Convention, where the crowd chanted: "Bring them home."

Goldberg-Polin's parents were among a number of hostages' families who protested in Kibbutz Nirim, near the border with Gaza, on Thursday to demand to secure their release. 

"Hersh, it's dada," yelled Jon Polin.

"What you need to know, and all 107 of you need to know, is not only are the families here today and nine million people of this country, but people all over the world are fighting for you," he said.

His mother, Rachel Goldberg, raised her hand to the sky as she spoke into the microphone: "We love you. Stay strong. Survive."

WATCH | Hersh Goldberg-Polin's parents speak in June about hopes for son to be released:

'These are human beings,' parents of Israeli hostage say

The parents of Hersh Goldberg-Polin, who was taken hostage on Oct. 7 at Nova music festival during the Hamas-led attacks on southern Israel, say they hope newly released footage of his capture brings a deal for the release of all hostages closer to fruition.