GAZA STRIP, Palestinian Territories: Hamas said Sunday its fighters were engaged in “heavy fighting” in Gaza where Israel has escalated ground operations, as calls multiply to deliver aid to the Palestinian territory after weeks of siege and bombardment.

World leaders underlined the urgency of increasing aid into the Hamas-controlled territory and protesters worldwide rallied for a cease-fire, after Israeli Prime Minister Benjamin Netanyahu steeled his nation for a “long and difficult war.”

Despite calls for a humanitarian truce, international outrage and the potential risk to hostages held in Gaza, Israel has intensified the war triggered by Hamas’s unprecedented attack.

Hamas militants stormed across the Gaza border on October 7 in the deadliest attack in Israel’s history, killing 1,400 people, mostly civilians, and kidnapping 239 others including many migrant workers, according to the latest figures provided Sunday by army spokesman Daniel Hagari.

The Hamas-run health ministry in Gaza says the retaliatory Israeli bombardment has killed more than 8,000 people, mainly civilians and half of them children.

Panic and fear have surged inside the Palestinian territory, where the UN says more than half of its 2.4 million residents are displaced and thousands of buildings destroyed.

Hamas’s armed wing, the Ezzedine Al-Qassam Brigades, said on Sunday its fighters were “engaged in heavy fighting... with the invading occupation (Israeli) forces in northwest Gaza.”

Israel’s army said a new “stage” of the war started with ground incursions since late Friday, an escalation from two brief operations earlier in the week.

In a phone call with Netanyahu on Sunday, US President Joe Biden “underscored the need to immediately and significantly increase the flow of humanitarian assistance to meet the needs of civilians in Gaza,” according to a readout of the conversation from the White House.

And in a separate call with President Abdel Fattah El-Sisi of Egypt, which borders Gaza to the south, the two leaders “committed to the significant acceleration and increase of assistance,” the White House said.

UN chief Antonio Guterres said the situation was “growing more desperate by the hour” as casualties increase and essential supplies of food, water, medicine and shelter dwindle.

Top Hamas official Musa Abu Marzouk in a statement Sunday called on Egypt to take “decisive” action to speed up aid to Gaza.

“Egypt should not remain a spectator. We expect a decisive stance by Egypt allowing aid to enter Gaza as soon as possible,” he said.

The Palestinian Red Crescent Society said Israel was repeatedly bombing around Al-Quds hospital in central Gaza, causing damage and putting civilians at risk.

Mohamed Al-Talmas, who has taken shelter in Gaza’s biggest hospital Shifa, said “the ground shook” with intense Israeli raids.

The UN agency for Palestinian refugees, UNRWA, said “thousands of people” broke into several of its warehouses and distribution centers in Gaza, grabbing basic items like flour and hygiene supplies.

“This is a worrying sign that civil order is starting to break down,” it said.

A US government official, speaking on condition of anonymity, said earlier Israel was committed to allowing 100 to aid trucks into Gaza daily — a figure the UN has said was needed to meet the most basic needs.

On Sunday Israel’s military said it had struck hundreds of Hamas targets and increased its ground forces in Gaza. Military spokesman Hagari vowed to “chase down” Hamas’s leader in Gaza, Yahya Sinwar.

The army said troops had “confronted” militants who emerged out of a tunnel in north Gaza, highlighting challenges in Hamas’s vast underground network to Israel’s ground operation.

In a late-night televised address on Saturday, Netanyahu announced a “second stage of the war” to “eradicate” Hamas, the Palestinian Islamist movement that has governed Gaza since 2007.

Communications were down in Gaza after Israel cut Internet lines ahead of the intensification of its operations, although connectivity was gradually returning on Sunday.

The “burden” lies with Israel to distinguish between militants and innocent civilians in Gaza, US National Security Adviser Jake Sullivan told CNN television.

Hagari again urged Palestinian civilians to go south “to a safer area,” but residents remained wary as air strikes continue.

Ibrahim Shandoughli, a 53-year-old from Jabaliya in northern Gaza, told AFP he and his family went nowhere.

“Where do you want us to evacuate to? All the areas are dangerous.”

In Israel, sympathy has swelled for the families whose loved ones were abducted by Hamas and are at heightened risk as the war intensifies.

Hamas has released four hostages, but this week said “almost 50” had been killed by Israeli strikes, a claim that was impossible to verify.

“We demanded that no action be taken that endangers the fate of our family members,” said Meirav Leshem Gonen, the mother of hostage Romi Gonen.

After Hamas said it was prepared to release the hostages if Israel freed the Palestinian prisoners it was holding, Israel’s Defense Minister Yoav Gallant accused the group of playing “psychological games.”

“Hamas is cynically using those who are dear to us — they understand the pain and the pressure,” Gallant told relatives of hostages, according to a statement released by his office.

Ifat Kalderon, whose relatives are believed held in Gaza, told AFP she supported the idea of a prisoner release in exchange for the hostages.

“Take them, we don’t need them here,” she said, referring to Palestinian detainees.

The ground operations have heightened fears that Israel’s other enemies — the Iran-allied “axis of resistance” forces in Lebanon, Syria, Iraq and Yemen — could enter the conflict.

Iran’s President Ebrahim Raisi warned on X, formerly Twitter, that Israel’s “crimes have crossed the red lines, which may force everyone to take action.”

Top ally the United States has warned Israel’s enemies to stay out and strengthened its military presence in the region.

Skirmishes have intensified on the Israeli-Lebanese border with Iran-backed Hamas ally Hezbollah, raising fears of a new front.

On Sunday militants in south Lebanon fired rockets toward Israel, which has responded with strikes, in a fresh escalation along the border.

Violence has also spiked in the occupied West Bank since the October 7 attacks, with more than 110 Palestinians killed, according to the territory’s health ministry.