Medics in Gaza warned on Sunday that thousands could die if hospitals packed with wounded people run out of fuel and basic supplies, as civilians struggled to find food, water and safety ahead of an expected Israeli ground offensive in the war sparked by Hamas' deadly attack last week.

Israeli forces, supported by a growing deployment of US warships in the region, positioned themselves along Gaza's border and drilled for what Israel said would be a broad campaign to dismantle the militant group.

A week of blistering airstrikes have demolished entire neighbourhoods but failed to stem militant rocket fire into Israel.

The Gaza Health Ministry said 2,329 Palestinians have been killed since the fighting erupted, more than in the 2014 Gaza war, which lasted over six weeks. That makes this the deadliest of the five Gaza wars for both sides.

More than 1,300 Israelis have been killed, the vast majority of them civilians killed in Hamas's October 7 assault. This is the deadliest war for Israel since the 1973 conflict with Egypt and Syria.

Israel dropped leaflets over Gaza City in the north and renewed warnings on social media, ordering more than 1 million Palestinians — almost half the territory's population — to move south. The military says it is trying to clear away civilians ahead of a major campaign against Hamas militants in the north, including in what it said were underground hideouts in Gaza City. Hamas urged people to stay in their homes.

The military said on Sunday that it would refrain from targeting a single route south from 10 am to 1 pm, again urging Palestinians to leave the north en masse. The military offered two corridors and a longer window the day before. It says hundreds of thousands have already fled south.

Hezbollah fighters in Lebanon meanwhile fired an anti-tank missile toward an Israeli army post and Israel responded with artillery fire. Israel's Magen David Adom rescue service said a 40-year-old man was killed, without giving his nationality. Israel later closed off areas up to 4 kilometers (2.5 miles) from the border and ordered civilians within 2 kilometers to shelter in safe rooms.

Israel and Hezbollah, which fought a devastating war in 2006, have traded fire along the border several times since the start of the latest Gaza war.

The UN and aid groups have said that the mass exodus within Gaza, along with Israel's complete siege of the 40-kilometer-long (25-mile-long) coastal territory, would cause untold human suffering.

The World Health Organization said the evacuation “could be tantamount to a death sentence” for the more than 2,000 patients in northern hospitals, including newborns in incubators and people in intensive care.

Gaza's hospitals are expected to run out of generator fuel within two days, according to the UN, which said that that would endanger the lives of thousands of patients.

In Nasser Hospital in the southern town of Khan Younis, Gaza's second largest after al-Shifa, intensive care rooms are packed with wounded patients, most of them children below the age of three. Hundreds of people with severe blast injuries have come to the hospital, where fuel is expected to run out by Monday, said Dr. Mohammed Qandeel, a consultant at the critical care complex.

There are 35 patients in the ICU that depend on ventilators to stay alive and another 60 on dialysis. If fuel runs out, “it means the whole health system will be shut down, the services will be off,” he said.

“We we are talking about another catastrophe, another war crime, a historical tragedy," he said, as children moaned in pain in the background. “All these patients are in danger of death if the electricity is cut off,” he said.

In the Kamal Alwan Hospital in the northern Gaza Strip, Dr. Hussam Abu Safiya, the head of paediatrics, said the hospital did not evacuate despite the Israeli order because there was no way to move patients elsewhere without risking their lives. There are seven newborns in the ICU hooked up to ventilators, he said. “We cannot evacuate, it would mean their death and other patients under our care.”

And wounded patients keep coming in with severed limbs, severe burns and other life-threatening injuries. “It's frightening,” he said.

Gaza was already in a humanitarian crisis due to a growing shortage of water and medical supplies caused by the Israeli siege, which has also forced the enclave's sole electrical plant to shut down. With some bakeries closing, residents said they were unable to buy bread.

The US has been trying to broker a deal to reopen Egypt's Rafah crossing with Gaza to allow Americans and other foreigners to leave and humanitarian aid amassed on the Egyptian side to be brought in. The crossing, which was closed because of airstrikes early in the war, has yet to reopen.

Hundreds of relatives of the estimated 150 people captured by Hamas in Israel and taken to Gaza meanwhile gathered outside the Israeli Defense Ministry in Tel Aviv, demanding their release.

“This is my cry out to the world: Please help bring my family, my wife and three kids,” said Avihai Brodtz of Kfar Azza. Many expressed anger toward the government, saying they still have no information about their loved ones.

In a televised address Saturday night, Israel's chief military spokesman, Rear Adm. Daniel Hagari, accused Hamas of trying to use civilians as human shields.

“We are going to attack Gaza City very broadly soon,” he said, without giving a timetable for the attack.

When asked at a press briefing whether Israel would treat civilians who stay in the north as combatants, Lt. Col. Richard Hecht, another army spokesman, said: “That's why we've encouraged people not involved with Hamas to move south.”

The military said Sunday an airstrike in southern Gaza had killed a Hamas commander blamed for the killings at Nirim, one of several communities Hamas had attacked in southern Israel. Israel said it struck over 100 military targets overnight, including command centers and rocket launchers.

Israel has called up some 360,000 military reserves and massed troops and tanks along the border with Gaza. Israelis living near the Gaza border, including residents of the town of Sderot, continued to be evacuated. Militants in Gaza have fired over 5,500 rockets since the hostilities erupted, many reaching reaching deep into Israel, as Israeli warplanes pound Gaza.

US Defense Secretary Lloyd Austin said late Saturday that the US was moving a second carrier strike group, the USS Dwight D. Eisenhower, to the eastern Mediterranean, in a show of force meant to deter any allies of Hamas, such as Iran or Lebanon's Hezbollah militant group, from seeking to widen the war.

US Secretary of State Antony Blinken meanwhile met with Saudi Arabia's Crown Prince Mohammed bin Salman in Riyadh as the Biden administration scrambles to prevent a wider regional conflict. Prince Mohammed is the sixth Arab leader Blinken has met since he arrived in the Middle East Thursday.

Hamas remained defiant. In a televised speech Saturday, Ismail Haniyeh, a top official based abroad, said that “all the massacres” will not break the Palestinian people.

Hamas spokesperson Jihad Taha told The Associated Press in Beirut that Israel “does not dare to fight a ground battle," because of the captives. He alluded to the possible entry of Hezbollah and other regional players in the battle should Israel launch a ground invasion but declined to say whether they had made any concrete commitments.

An Israeli airstrike near the Jabaliya refugee camp in northern Gaza killed at least 27 people and wounded another 80, Gaza health authorities said.

Most of the victims were women and children, the authorities said. Doctors from Kamal Edwan Hospital shared footage of charred and disfigured bodies.

It was not clear how many Palestinians remained in northern Gaza by Saturday afternoon, said Juliette Touma, a spokesperson for the UN agency for Palestinian refugees. An estimated 1 million people have been displaced in Gaza in one week, she said.

At Gaza City's main hospital, al-Shifa, a crowd of men, women and children that medical officials estimated at 35,000 crammed into the hospital's lobby and bloodied hallways and under the trees on the hospital grounds, hoping the facility would be spared in the coming attack.

“People think this is the only safe space after their homes were destroyed and they were forced to flee,” said Dr. Medhat Abbas, a Health Ministry official.

Basic necessities, including water, were running out because of the siege, which Israel has said will only be lifted when the captives are returned.

The Israeli military's evacuation order demands the territory's entire population cram into the southern half of Gaza as Israel continues strikes, including in the south. The Hamas communications office said Israel has destroyed over 7,000 housing units so far.

Al-Shifa hospital was receiving hundreds of wounded every hour and had used up 95 per cent of its medical supplies, hospital director Mohammad Abu Selim said. Water is scarce and the fuel powering its generators is dwindling.

“The situation inside the hospital is miserable in every sense of the word,” he said. “The operating rooms don't stop.”