A weapon used in a strike on a UNRWA school sheltering displaced people on June 6 appears to be U.S.-made, three munitions experts told ABC News.

Journalist Emad Abu Shawiesh captured video of weapons fragments at the UNRWA al Sardi school building in Nuseirat in Gaza on June 6.

The weapon fragments seen in the video are consistent with the nose section of a U.S.-made GBU-39 "Small Diameter Bomb," Trevor Ball, a former U.S. Army explosive ordinance disposal specialist, told ABC News.

The GBU-39 also appeared to have been employed in a deadly strike on May 26 in Rafah, Gaza, according to Ball and another munitions expert, who asked not to be named due to the sensitivity of the issue.

Mark Hiznay, an associate director with the Crisis, Conflict and Arms Division of Human Rights Watch, told ABC News the image shows the remnants of a GBU-39.

N.R. Jenzen-Jones, a director at the consultancy Armament Research Services, said the image was consistent with the Small Diameter Bomb series.

“Given what we know about the IDF arsenal and munitions used in previous strikes, the remnants are most likely from a GBU-39 SDB and include a portion of the nose (forward section) of the bomb,” Jenzen-Jones said, adding that other munitions could have been used in the strike, which he had not yet assessed in detail.

-ABC News Chris Looft

The U.S. State Department has sanctioned a militant Palestinian group operating in the West Bank known as "Lions’ Den," it announced Thursday.

The department said the group claimed responsibility for several drive-by shootings around Nablus in 2022, injured and killed Palestinian civilians during clashes with Palestinian Authority Security forces that same year, and that its fighters reportedly targeted Israeli forces at a checkpoint this past April.

The Lions’ Den was the target of an Israeli raid in February. The group has been blamed for much of the surging violence in the West Bank during recent months.

"The United States condemns any and all acts of violence committed in the West Bank, whoever the perpetrators, and we will use the tools at our disposal to expose and hold accountable those who threaten peace and stability there," State Department spokesperson Matt Miller said.

The Biden administration has also imposed a number of sanctions on Israeli West Bank settlers earlier this year; targets include organizations accused of fundraising for extremist settlers and allies of Israel’s far-right National Security Minister Itamar Ben-Gvir.

-ABC News' Shannon Crawford

The United States and 16 other countries released a joint statement this morning calling on Hamas to accept a cease-fire proposal and hostage release deal outlined by President Joe Biden.

"We note that this agreement would lead to an immediate ceasefire and rehabilitation of Gaza together with security assurances for Israelis, and Palestinians, and opportunities for a more enduring long-term peace and a two-state solution," the joint statement said.

The statement was issued by leaders of the United States, Argentina, Austria, Brazil, Bulgaria, Canada, Colombia, Denmark, France, Germany, Poland, Portugal, Romania, Serbia, Spain, Thailand and the United Kingdom.

-ABC News' Justin Gomez and Kevin Shalvey

Dozens of people were killed and scores were injured in an Israeli strike on a school in Gaza, the local U.N. agency said on Thursday.

The Israel Defense Forces confirmed the airstrike, saying the school had a Hamas compound "embedded inside" of it.

"Hamas and Islamic Jihad terrorists who belonged to the Nukhba Forces and took part in the murderous attack on communities in southern Israel on October 7th were operating in the compound," IDF officials said in a statement.

The death toll was expected to be be 35 and 45 people, the U.N. Agency for Palestine Refugees said, adding that it had not yet been able to independently verify those figures.

The school in the Nuseirat area, near central Gaza, was struck overnight or early in the morning on Thursday, UNRWA said. There were possibly a few strikes, the agency said.

IDF officials said they had taken measures to "to reduce the risk of harming uninvolved civilians during the strike, including conducting aerial surveillance, and additional intelligence information."

- ABC News’ Victoria Beaule and Kevin Shalvey

An Israeli government official said the Israeli Prime Minister’s Office wasn’t informed that President Joe Biden’s Friday remarks would include a permanent end to the fighting.

“If you listen to what Biden said, you come to the impression that we agree to a permanent cease-fire without, or, without our conditions being met, and that's not the case,” the official said.

The official said the Israeli Prime Minister’s Office, including Prime Minister Benjamin Netanyahu, was informed 30 minutes before that Biden was giving a speech. The official said Netanyahu was told that the speech would focus on the hostages, with no mention of implementing a permanent cease-fire.

A senior U.S. official said the Biden administration "engaged with the Israelis at multiple levels before the president delivered the speech." The official said the U.S. specifically engaged with the Israeli Prime Minister's Office and the Israeli war cabinet.

The official also pointed to when Biden said in his speech that it was a proposal that the Israelis agreed to. The official noted that Netanyahu himself said that it was an Israeli proposal.

An Israeli official and two other Israeli sources who are familiar with the matter told ABC News that what Biden presented is indeed the outline of the Israeli proposal. The sources said the proposal was approved by all war cabinet members, including Netanyahu, and sent to the mediators earlier in the week.

The sources added that there are “interpretation gaps,” referring to the way the outline was presented by Biden.

Biden presented on Friday what he said was an Israeli proposal to draw the war in Gaza to a close.

Biden said the deal had been transmitted to Israel and Hamas, through Qatar.

The president said the first phase would last for six weeks and include a "full and complete cease-fire, a withdrawal of Israeli forces from all populated areas of Gaza [and] release of a number of hostages." Palestinians would also be able to return to their homes and 600 trucks of humanitarian aid would be delivered to Gaza every day.

The second phase would include a release of all remaining living hostages and the temporary cease-fire would become a permanent cease-fire with Israel withdrawing all forces from Gaza "as long as Hamas lives up to its commitments," Biden said.

In phase three, there would be a major reconstruction of Gaza.

-ABC News’ Britt Clennett, Dana Savir and Michelle Stoddart