At least 274 people were killed in central Gaza on Saturday as the Israeli military moved into the Nuseirat camp to rescue four hostages, the Hamas-run Gaza Health Ministry said Sunday.

Another 698 people were injured as Israeli forces entered the refugee camp, the ministry said.

Some of the injured were in critical condition, the ministry said.

The death toll in Gaza climbed on Saturday to 37,084 people, the ministry said. More than 84,000 others have been injured, the ministry said.

-ABC News’ Victoria Beaule and Kevin Shalvey

U.S. Central Command (USCENTCOM) announced Saturday that it began delivery of humanitarian assistance ashore in Gaza.

"Today, a total of approximately 492 metric tons (~1.1 million pounds) of much needed humanitarian assistance was delivered to the people of Gaza," CENTCOM said in a statement.

No U.S. personnel went ashore to Gaza, according to CENTCOM.

The agency said it has so far assisted in the delivery of more than 1,573 metric tons of humanitarian aid to organizations operating on the ground in Gaza.

-ABC News' Nathan Luna

Secretary of State Antony Blinken released a statement Saturday following the rescue of four Israeli hostages, welcoming their safe return.

"The United States will not rest until every hostage is returned home," he said.

Blinken also pushed for the cease-fire announced last week by President Joe Biden.

He contended would "bring relief to both the people of Gaza and the remaining hostages and their families through an immediate ceasefire that could lead to the release of all hostages, a surge of humanitarian assistance, Gaza’s reconstruction, and an enduring end to the war."

"The only thing standing in the way of achieving this ceasefire is Hamas. It is time for them to accept the deal," he said.

A U.S. defense official provided ABC News with some more details about the operation.

The official said the recently constructed JLOTS pier, which is used for transporting humanitarian supplies, was not used in the operation.

"An area south of the facility was used to safely return the hostages to Israel. Any such claim to the contrary is false," the official said.

-ABC News' Nathan Luna

After meeting with rescued hostages and their families, Israeli Prime Minister Benjamin Netanyahu called the rescue operation "remarkable" and told reporters they will do "whatever it takes" to get the hostages back.

"We're committed to getting the release of all the hostages, and we expect Hamas to release them all — but if they don't, we'll do whatever it takes to get them all back home. Hamas is committing war crimes every day, including the holding of these hostage.s. Our soldiers are performing in the most valiant and moral way to end this war with a victory against these killers and against these kidnappers, and we shall prevail," Netanyahu said.

Earlier, the Israel Defense Forces said the hostages were being held in civilian populated areas, without any way to reach them but go through Gaza civilians, IDF spokesman Daniel Hagari told reporters. Three male hostages were held together in an apartment and a fourth female hostage was held in another apartment just over 650 feet away, Hagari said.

At least 150 Palestinians were killed in Israeli raids on Saturday, the Hamas-run Gaza Health Ministry said.

A United States official provided ABC News with more details about the rescue efforts, noting that the U.S. has been providing regular intelligence sharing and expertise on hostage recovery efforts since Oct. 7.

The official stressed there were no American boots on the ground as part of this effort.

-ABC News' Dana Savir, Bruno Nota and Molly Nagle

The U.S. continues to push Hamas to agree to the cease-fire proposal President Joe Biden outlined Friday, saying Hamas' stated opposition to the deal has yet to be officially transmitted.

"We've seen some public comments from Hamas officials, but we have not yet gotten an official response from Hamas to the Qataris, who are the mediator to whom Israel gave their proposal that was transmitted to Hamas," White House national security adviser Jake Sullivan told ABC's George Stephanopoulos on "Good Morning America" Wednesday.

"The ball is in Hamas's court," Sullivan continued. "Israel has accepted the proposal. The world has endorsed the proposal. Now it's time for Hamas to say yes to it."

Sullivan argued the latest multi-phase proposal is key to ending the war, returning hostages, and increasing the flow of aid into Gaza, while ensuring Israel's security and a better future for Palestinians.

"That's what's on offer," Sullivan said. "That's what Hamas needs to step up and take and we're awaiting to get their official response."

Asked whether Biden thinks Israeli Prime Minister Benjamin Netanyahu was prolonging the war for political gain — which he suggested in a Time magazine interview out Tuesday — Sullivan pointed to Biden's answer to a question Tuesday evening asking if Netanyahu was playing politics.

"I don't think so. He's trying to work out the serious problem he has," Biden said Tuesday.

"And from our perspective, we're not going to delve into Israeli politics," Sullivan added. "What we're going to do is focus on the fundamental task at hand, which is President Biden's effort to end this war, get the hostages home, make sure Israel's safe and make sure the Palestinian people have a decent future."

-ABC News' Fritz Farrow