The Israeli military said Sunday its ground offensive had expanded to every part of Gaza, and it ordered more evacuations in the crowded south while vowing that operations there against Hamas would be “no less strength” than its shattering ones in the north.

Heavy bombardment followed the evacuation orders, and Palestinians said they were running out of places to go in the sealed-off territory bordering Israel and Egypt. Many of Gaza's 2.3 million people are crammed into the south after Israel ordered civilians to leave the north in the early days of the war, which was sparked by the Oct. 7 Hamas-led attack in Israel that killed about 1,200, mostly civilians.

The United Nations estimates that 1.8 million Palestinians in Gaza have been displaced. Nearly 958,000 of them are in 99 U.N. facilities in the south, said Juliette Toma, director of communications at the U.N. agency for Palestinian refugees.

After dark, gunfire and shelling were heard in the central town of Deir al-Balah as flares lit the sky. In Gaza’s second-largest city of Khan Younis, Israeli drones buzzed overhead. U.N. human rights chief Volker Türk urged an end to the war, saying civilian suffering was “too much to bear.”

The Health Ministry in Hamas-run Gaza said the death toll there since Oct. 7 has surpassed 15,500, with more than 41,000 wounded. The ministry does not differentiate between civilian and combatant deaths, but said 70% of the dead were women and children.

A Health Ministry spokesman asserted that hundreds had been killed or wounded since a weeklong cease-fire ended Friday. “The majority of victims are still under the rubble,” Ashraf al-Qidra said.

Fears of a wider conflict intensified. A U.S. warship and multiple commercial ships came under attack in the Red Sea, the Pentagon said. Yemen’s Iran-backed Houthi rebels claimed attacks on two ships they described as being linked to Israel but did not acknowledge targeting a U.S. vessel.

Hopes for another temporary truce in Gaza were fading. The cease-fire facilitated the release of dozens of the roughly 240 Gaza-held Israeli and foreign hostages in exchange for Palestinians imprisoned by Israel. But Israel has called its negotiators home, and Prime Minister Benjamin Netanyahu says the war will continue until “all its goals” are achieved. One is to remove Hamas from power in Gaza.

Senior Hamas official Osama Hamdan said resuming talks with Israel on further exchanges must be tied to a permanent cease-fire.

White House National Security Council spokesman John Kirby told NBC’s “Meet the Press” the U.S. was working "really hard” for a resumption of negotiations.

Israel's military widened evacuation orders in and around Khan Younis in the south, telling residents of at least five more areas to leave. Residents said the military dropped leaflets calling Khan Younis "a dangerous combat zone" and ordering them to move to the border city of Rafah or a coastal area in the southwest.

But Halima Abdel-Rahman, a widow and mother of four, said she won’t heed such orders anymore. She fled her home in October to an area outside Khan Younis, where she stays with relatives.

“The occupation tells you to go to this area, then they bomb it,” she said by phone. "The reality is that no place is safe in Gaza. They kill people in the north. They kill people in the south.”

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The United States, Israel’s closest ally, has urged Israel to avoid significant new mass displacement and to do more to protect civilians. U.S. Vice President Kamala Harris told Egypt's president that “under no circumstances” would the U.S. permit the forced relocation of Palestinians from Gaza or the West Bank, an ongoing siege of Gaza or the redrawing of its borders. As Harris flew from Dubai and an appearance at the U.N. climate conference back to Washington, she spoke by phone with Israeli President Isaac Herzog. They discussed the situation in the West Bank, with Harris reiterating U.S. concerns with steps being taken that could escalate tensions — including extremist settler violence, according to a summary provided by Harris’ office.

Harris also spoke by phone during the flight to Mahmoud Abbas, head of the Palestinian Authority, and again stated U.S. support for the Palestinian peoples’ right to security, dignity and self-determination, according to the summary.

The vice president’s national security adviser, Phil Gordon, stayed behind in Dubai, and planned to travel to Israel and the West Bank this week to continue to discuss U.S. commitment to a two-state solution in post-war Gaza.

On the ground in Gaza, there was fear and mourning. Outside a Gaza City hospital, a dust-covered boy named Saaed Khalid Shehta dropped to his knees beside the bloodied body of his little brother Mohammad, one of several bodies laid out after people said their street was hit by airstrikes. He kissed him.

“You bury me with him!” the boy cried. A health worker at Al-Ahli Baptist Hospital said more than 15 children were killed.

Israel's military said its fighter jets and helicopters struck targets in Gaza including “tunnel shafts, command centers and weapons storage facilities." It acknowledged "extensive aerial attacks in the Khan Younis area."

The bodies of 31 people killed in the bombardment of central Gaza were taken to the Al-Aqsa hospital in Deir al-Balah, said Omar al-Darawi, a hospital administrative employee. One woman wept, cradling a child’s body. Another carried the body of a baby. Later, hospital workers reported 11 more dead after another airstrike. Bloodied survivors included a child carried in on a mattress.

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Outside a hospital morgue in Khan Younis, resident Samy al-Najeila carried the body of a child. He said his sons had been preparing to evacuate their home, “but the occupation didn’t give us any time. The three-floor building was destroyed completely, the whole block was totally destroyed.” He said six of the bodies were his relatives.

“Five people are still under the rubble,” he said. “God help us.”

In a video from the same crowded al-Nasser hospital, UNICEF spokesperson James Elder said: “I feel like I’m almost failing in my ability to convey the endless killing of children here.”

Israel says it does not target civilians and has taken measures to protect them, including its evacuation orders. In addition to leaflets, the military has used phone calls and radio and TV broadcasts to urge people to move from specific areas.

Israel says it targets Hamas operatives and blames civilian casualties on the militants, accusing them of operating in residential neighborhoods. It claims to have killed thousands of militants, without providing evidence. Israel says at least 78 of its soldiers have been killed,

The widening offensive likely will further complicate humanitarian aid to Gaza. Wael Abu Omar, a spokesman for the Palestinian Crossings Authority, said 100 aid trucks entered Sunday, but U.N. agencies have said 500 trucks per day on average entered before the war.

Read more: Palestinian death toll in Gaza tops 15,200

The renewed hostilities also heightened concerns for the 137 hostages the Israeli military believes are still being held by Hamas. During the recent truce, 105 hostages were freed, and Israel released 240 Palestinian prisoners. Most of those released by both sides were women and children.

Elsewhere in the region, Lebanon's militant Hezbollah group said it struck Israeli positions near the tense Lebanon-Israel border. Eight soldiers and three civilians were wounded by Hezbollah fire in the area of Beit Hillel, army radio reported. The military said its artillery struck sources of fire from Lebanon and its fighter jets struck other Hezbollah targets.

Iraqi militants with the Iran-backed umbrella group the Islamic Resistance in Iraq said they struck the Kharab al-Jir U.S. military base in Syria with rockets. A U.S. military official, speaking on condition of anonymity in line with regulations, said rockets hit Rumalyn Landing Zone in Syria but there were no reports of casualties or damage.

Later Sunday, officials with Iranian-backed militias in Iraq said five militia members were killed in an airstrike blamed on the U.S. near Kirkuk. The officials spoke on condition of anonymity because they were not authorized to comment publicly. A U.S. official who spoke on condition of anonymity to discuss a military operation not yet made public said the U.S. had carried out a “self-defense strike” near Kirkuk targeting a drone staging site.