National security adviser Jake Sullivan said the U.S. is still having "intensive discussions" with "Israel, Qatar and Egypt about how to best get traction on a strategy that will get all the hostages out."

“The President and I, along with Secretary [of State Antony] Blinken and [CIA] Director [William] Burns, will stay in touch with our Israeli and Qatari counterparts, as well as our Egyptian counterparts, to press Hamas on this issue," Sullivan said. "Right now, Hamas is refusing to release civilian women who should have been part of the agreement. And it is that refusal by Hamas that has caused the end of the hostage agreement, and therefore, the end of the pause in hostilities."

Over 100 people remain hostage in Gaza. National Security Council spokesman John Kirby said Sunday the U.S. thinks "about eight" Americans remain hostage.

"Of course, for the United States, the paramount priority is getting the American hostages out and we are talking to the president about all of his options in terms of securing the release of American hostages," Sullivan said. "Beyond that, I'm not going to comment because we need to be able to have those sensitive, diplomatic discussions behind closed doors."

-ABC News' Molly Nagle

In a heated exchange with a reporter, State Department spokesman Matthew Miller said that while it's proven Hamas deliberately targeted civilians to kill, he said he has not seen evidence that Israel is deliberately killing civilians.

"I'm surprised I don't hear more people saying, 'Why doesn't Hamas lay down its arms? Why doesn't Hamas move out of schools?'" Miller said.

At a different point in the briefing, Miller said Secretary of State Antony Blinken told Israeli officials during his recent trip to Israel that the U.S. would like to see more precision and restraint in Israel's operations in southern Gaza, compared to the initial bombardment in northern Gaza, to limit civilian casualties.

"We've seen a much more targeted request for evacuations here, where the Israeli Defense Forces have identified specific neighborhoods where they plan to conduct military operations, and urged in advance of those operations that people in those neighborhoods to move, rather than telling an entire city or an entire region to vacate their homes. So that is an improvement on what's happened before," he said.

Miller added, "They have instructed them to move to areas that we know are deconfliction zones. It's one of the things we discussed with them last week."

-ABC News' Matt Seyler

The women and children freed from captivity in Gaza all lost between 10% to 15% of their body weight, according to Dr. Yael Moze from the Schneider Children's Medical Department.

One family took three showers during their 54 days held hostage, while one child hostage took no shower during all 54 days in captivity, Moze said.

Hostages also suffered psychological abuse, Moze said, recalling one teenager who was allegedly told he'd be held hostage for at least a year.

As Israel steps up its bombing campaign again, all telecommunications have been knocked out in the Gaza Strip, according to the Palestine Telecommunications Company, or Paltel.

"We regret to announce that all telecom services in Gaza Strip have been lost due to the cut off of main fiber routes. Gaza is blacked out again," Paltel said.

Israeli authorities say they have collated "hundreds of testimonies of rape and sex crimes" they claim was committed by Hamas militants during the Oct. 7 terror attack.

A document from the Israel Defense Forces details allegations of sexual violence, with "almost all of the testimonies" coming from eyewitnesses and first responders who were present at the scene during or after atrocities, the document states. This is because "virtually all" of the victims of sexual violence were also murdered on Oct. 7, according to the document.

The IDF said the document offers "only a small part of an immense body of information of evidence of Hamas' sex crimes" and said the evidence "proves beyond all doubt that Hamas and other … terrorists used rape and sexual violence systemically against Israeli women and children," according to the IDF.

One IDF volunteer quoted in the document described seeing many young women "in bloody, shredded rags, or just in underwear."

"Our team commander saw several (female) soldiers who were shot in the crotch and intimate areas," the IDF volunteer said, according to the document.

The IDF alleges that some members of Hamas who were captured and then interrogated also gave testimony that women were sexually abused on Oct. 7.

An Israeli paramedic quoted in the document said they inspected the bodies of two teenage girls who had been murdered. One of the girls "had her pants pulled down towards her knees ... and there's the remains of semen on the lower part of her back," the document states.

A survivor of the Oct. 7 attack, Gad Liebersohn, quoted in the document said that "for two hours I'm hiding and hearing people getting kidnapped and women getting raped ... begging for their lives."

Hamas, the militant group that governs the Gaza Strip, has denied the allegations that its fighters committed sexual violence during the Oct. 7 attack on neighboring southern Israel.

Cochav Elkayam-Levy, the head of Israel's Civil Commission on Oct. 7 Crimes by Hamas Against Women and Children, has described what she called "widespread rape evidence."

-ABC News' Tom Soufi Burridge