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Israel stepped up its bombardment of southern Gaza at the weekend as Palestinians scrambled to find shelter in the besieged enclave.
The Israeli military renewed its assault on Gaza on Friday after a seven-day truce with Hamas expired.
The focus of the campaign has shifted from northern Gaza to the southern half of the Strip, where hundreds of thousands of displaced Palestinians are sheltering. The Israeli military had previously told residents of northern Gaza to flee south to avoid being caught in the crossfire.
Israeli air strikes hit the southern cities of Khan Younis and Rafah on Sunday, as Hamas said it launched a barrage of rockets targeting Tel Aviv.
More than 700 Palestinians were killed across the Gaza Strip in a 24-hour period, officials said. Dozens were killed in a strike in the vicinity of the Al Amal school in the city of Khan Younis, local media reported.
There were no reported casualties from the Hamas missile attack against Israel.
Residents said they feared an imminent ground invasion of southern Gaza, after the Israeli military issued a statement ordering Palestinians to evacuate areas in and around the city of Khan Younis, instructing them to go west and south, towards the border with Egypt.
Conditions in one of the main hospitals in the city are already “beyond inadequate” and “unimaginable”, according to the World Health Organisation, whose officials visited Nasser Medical Hospital.
“Yesterday our team visited Nassar Medical Hospital in the south. It was packed with 1,000 patients - three times over its capacity. Countless people were seeking shelter, filling every corner of the facility,” said WHO chief Dr Tedros Ghebreyesus.
“Patients were receiving care on the floor, screaming in pain. These conditions are beyond inadequate - unimaginable for the provision of health care,” he wrote on X, formerly known as Twitter.
Dr Tedros repeated his call for an immediate ceasefire, amid mounting pressure on Israel to rein in its bombing campaign and re-engage in talks for a renewed truce with Hamas.
US Defence Secretary Lloyd Austin said Israel has a “moral responsibility and strategic imperative” to protect civilians in the Gaza Strip.
"If you drive them into the arms of the enemy, you replace a tactical victory with a strategic defeat," Mr Austin told a defence forum in Simi Valley, California.
The comments were his strongest warning to Israel, despite also pledging that the US would stand by Israel as its “closest friend in the world.”
US Vice President Kamala Harris also voiced concern over civilian suffering in Gaza.
"Frankly, the scale of civilian suffering, and the images and videos coming from Gaza, are devastating," Ms Harris told reporters at Cop28 in the UAE.
French President Emmanuel Macron took a similar tone as he travelled to Qatar, where talks between Israeli, Egyptian, Qatari and US officials had secured the previous truce and release of 110 hostages in exchange for 240 Palestinian detainees.
"We are at a moment when Israeli authorities must more precisely define their objectives and their final goal: the total destruction of Hamas, does anyone think it is possible? If this is the case, the war will last 10 years," he said on Saturday from the UAE, where he attended Cop28, before travelling to Doha.
France's Macron says he is going to work on new Gaza truce in Qatar
"There is no lasting security for Israel in the region if its security is achieved at the cost of Palestinian lives and thus of the resentment of public opinions in the region. Let's be collectively lucid," he said.
But hardliner allies of Israeli Prime Minister Benjamin Netanyahu say that Israel must continue with its war until it destroys Hamas.
Mr Netanyahu’s office said that Israeli negotiators had paused talks over the truce and the release of Israeli hostages in Gaza.
“We will continue the war until we achieve all its goals, and it’s impossible to achieve those goals without the ground operation,” he said in a televised news conference.
Hamas also currently has no plans for a truce until Israel stops its war in Gaza, according to Saleh Al Arouri, deputy head of the Palestinian group's political bureau.
"There will be no exchange of captives until the end of the aggression and a comprehensive and permanent ceasefire,” Mr Al Arouri told Al Jazeera.
