As the humanitarian crisis worsens in Gaza, Israeli Energy Minister Israel Katz said no electrical switch will be turned on, no water tap will be opened and no fuel truck will enter Gaza until the Israeli hostages are returned home.

Gaza relies on Israel for most of its power, which was cut off following the attack. Its sole power plant ran out of fuel on Wednesday.

The White House said there are no intentions to send U.S. troops to Israel.

"The Israelis have made it very clear that they don't want foreign troops on their soil. That they want to prosecute these operations on their own and they have every right to want to do that," said John Kirby, spokesperson for the National Security Council.

Kirby said the U.S. would "do everything we can to improve" the capabilities of the Israeli military.

And as humanitarian concerns grow in Gaza, Kirby told reporters that there are "ongoing conversations" with Israeli counterparts about the need for the "continued flow of humanitarian assistance" to the area.

-ABC News' Justin Gomez and Molly Nagle

The death toll of American citizens in Israel now stands at 27, John Kirby, spokesperson for the National Security Council, said at a White House briefing on Thursday.

Fourteen Americans remain unaccounted for.

At a news conference Thursday, Secretary of State Antony Blinken was asked about the gruesome photos and videos shown to him behind closed doors by Israeli Prime Minister Benjamin Netanyahu.

"It’s beyond what anyone would ever want to imagine, much less, God forbid, experience. A baby, an infant -- riddled with bullets. Soldiers beheaded. Young people, burned alive," he said. "I could go on, but it’s simply depravity in the worst imaginable way."

Blinken said that some of the images had been seen before, but others were new to him, and again said that Hamas’ acts harkened back to ISIS.

"I think for any human being to see this -- it’s really beyond almost anything that we can comprehend, digest," Blinken continued. "You can’t help but imagine yourself, your family, your loved ones, your friends in that situation, in that predicament and maybe the best word for it for me is overwhelming."

While some of the claims made by the IDF have been questioned and others have fueled online claims that the Israeli government is spreading disinformation, Blinken said that the photos would ultimately show exactly the horrors its people have confronted and serve to unify through "moral clarity."

-ABC News' Shannon Crawford

Fourteen staff members from the United Nations Agency for Palestine Refugees have been killed in airstrikes on the Gaza Strip, United Nations Relief and Works Agency Commissioner-General Philippe Lazzarini said during remarks from the UNRWA headquarters in Jerusalem on Sunday.

Most of the UNRWA's 13,000 staff members in the Gaza Strip have now been displaced or are "out of their homes," Lazzarini added.

Unless supplies are brought into Gaza, UNRWA and other international aid workers will not be able to continue humanitarian operations, Lazzarini said.

"As I speak with you, Gaza is running out of water and electricity," Lazzarini said.

At least 400,000 people who have been displaced in Gaza are currently sheltering in UNRWA schools and buildings, most of which have not been equipped as emergency shelters, Lazzarini said.

-ABC News' Ely Brown