Prime Minister Benjamin Netanyahu visited Israeli troops fighting in the Gaza Strip on Monday, vowing to stay the course of the war even with the death toll mounting. His trip came hours after Gazan health officials reported that a devastating overnight strike on a crowded neighborhood had killed dozens.

It was the Israeli leader’s second known visit to Gaza since the war began. Mr. Netanyahu has been facing increasing pressure from the United States to lower the intensity of the war, but he said on Monday that Israel would “deepen” the fighting in coming days.

The strike late Sunday in central Gaza underscored the risk to civilians as fighting intensifies. Gazans were mourning the victims in the neighborhood, Al Maghazi, where many who have fled fighting in other parts of the enclave have sought shelter.

Photos of the aftermath on Monday showed a gray concrete building gaping with dark holes where rooms used to be. At the foot of the building was a mound of debris, where men appeared to be digging for survivors, or bodies, without the aid of any heavy equipment.

The Gaza Health Ministry initially said 70 people had died in Sunday’s attacks on Al Maghazi, with many others still buried. But the difficulty of reaching residents in Gaza, where electricity shortages and communications blackouts have frequently obscured the picture of the war’s fallout, meant the details were blurry.

Gazan Health Ministry officials blamed Israeli airstrikes for the deadly attack on Al Maghazi. Israel’s military said Monday it was reviewing the episode.

Mohammed Abed, 36, a journalist from Al Maghazi, said he saw bodies among the collapsed buildings. He said he had been told there were about seven strikes on the area, including four on residential buildings. The damage, he said, strewed the entrances to the neighborhood with so much debris that people could not easily enter or exit.

Mr. Abed said one man, named Moen Ziyadeh, had been pulled from the rubble, still alive. But, he said, there were too many others to tend to, too many wounded and too few ambulances. Mr. Abed said he had watched Mr. Ziyadeh succumb to his wounds and die.

“These rockets, it’s like they’re made to destroy mountains, not people,” said another resident, Mohamed Abu Shaah, who had taken shelter at an acquaintance’s house in Al Maghazi with his wife and seven daughters.

As the Gazan death toll has soared and civilians have been pushed into smaller and smaller corners of the enclave, international calls for a cease-fire have grown. While Mr. Netanyahu’s government has said it is planning for a new phase of the fighting, the Israeli leader has repeatedly insisted that his military will keep up the war in Gaza until all of its goals are achieved.

“We’re not stopping, we are continuing to fight and are deepening the fighting in the coming days,” he said in a statement released by his Likud party on Monday, adding that “this will be a long battle, and it is not close to ending.”

Mr. Netanyahu is under sustained pressure from the Israeli public to free the remaining hostages who were seized during the Hamas-led attack on Israel on Oct. 7. That goal, which would likely entail negotiations with Hamas, is potentially at odds with the prime minister’s other avowed objective of wholly destroying the militant group.

After returning from Gaza on Monday, Mr. Netanyahu argued that military pressure had been critical to securing the release of about 100 hostages in a November exchange and that a sustained military campaign would be necessary to free those Israelis still in captivity.

“We won’t succeed in releasing all of the hostages without military pressure,” Mr. Netanyahu said in an address to the Knesset, Israel’s Parliament. “We won’t stop fighting.”

Toward the end of his speech, a chant arose from the viewing gallery, where family members of the hostages were seated. “Now! Now! Now,” people shouted as Mr. Netanyahu spoke.

Israeli forces are pushing farther into central Gaza while also continuing to battle Hamas fighters in the enclave’s north and south. Many places in central and southern Gaza are crowded with people who have fled their homes — multiple times, in many cases.

Mr. Abed, the journalist from Al Maghazi, said many people from neighboring areas had gone to there after obeying evacuation orders from the Israeli military. Al Maghazi does not appear on the evacuation orders the Israeli military has shared on social media in recent days, according to a review of its posts, leading Gazans, Mr. Abed said, to believe that it would be safe.

Homes in Al Maghazi are now routinely shared by dozens of people, Gazans say.

Mr. Abu Shaah said the influx of the newly displaced meant it was common for 20 people to crowd into a single room to sleep at night. It was the fifth time his family had packed up and rushed to a new place after fighting and airstrikes threatened a place they had taken shelter.

“We are doing everything we can just to run for our lives,” he said.

The rising death toll in Gaza, which health ministry officials have said stands at about 20,000 people, prompted Pope Francis on Monday to focus his Christmas address in part on the plight of Palestinians, as well as on Israeli hostages held in Gaza.

He mentioned Bethlehem, the holy city in the Israeli-occupied West Bank where officials have largely canceled Christmas festivities in solidarity with Palestinians in Gaza, and pleaded for peace to “come in Israel and the Palestinian territories, where war is devastating the lives of those peoples.”

The pope also called for “an end to the military operations, with their appalling harvest of innocent civilian victims,” and “for a solution to the desperate humanitarian situation by an opening to the provision of humanitarian aid.”

Gaza is controlled by Hamas, the armed group that led the Oct. 7 attacks on Israel that Israeli officials say killed about 1,200 people.

Mr. Abu Shaah said he had just returned from prayer late Sunday night and was about to put his daughters to sleep in the bed that nine of them shared when they heard a loud thud. Afraid they would find themselves under the rubble, they ran downstairs to a scene of devastation.

“We’ve seen a lot, but this is beyond anything we could have imagined,” he said. “Today my family and I are alive, but what about tomorrow?”

Before the war, about 33,000 Palestinians lived in Al Maghazi, an area covering only about a quarter of a square mile, according to the United Nations agency that aids Palestinians. Most families in the neighborhood were originally from villages in the center and south of what was Palestine before they fled or were forcibly displaced in the 1948 war that surrounded Israel’s establishment as a state.

The neighborhood has been hit multiple times before, according to U.N. reports.

Save the Children, an aid group, called the strike on Al Maghazi “another episode of the ongoing horror” in Gaza.

“Families and children are not targets and must be protected,” it said. “We need an immediate and definitive cease-fire to end this misery.”

Jason Horowitz contributed reporting from Rome and Nada Rashwan from Cairo.