Israel said on Saturday its war with Hamas had "entered a new phase" as the army relentlessly pounded Gaza three weeks into a conflict sparked by the deadliest attack in the country's history.
The United Nations warned thousands more civilians could die as Israel escalated ground operations in the Hamas-run Palestinian territory, where rescuers said fierce overnight bombardment destroyed hundreds of buildings.
Israel unleashed its bombing campaign after Hamas gunmen stormed across the Gaza border on October 7, killing 1,400 people, mostly civilians, and seizing more than 220 hostages, according to Israeli officials.
The Hamas-controlled health ministry in Gaza said Israeli strikes had killed 7,703 people, mainly civilians, with more than 3,500 of them children.
The conflict is the fifth and deadliest in Gaza since Israel unilaterally withdrew troops and settlers from the Palestinian territory in 2005.
UN human rights chief Volker Turk warned of "the possibly catastrophic consequences of large-scale ground operations in Gaza", saying "thousands more civilians" could die.
The intense Israeli strikes against Hamas, the Islamist group that has ruled Gaza since 2007, coincided with ground operations and came as tens of thousands of troops massed along the Gaza border ahead of an expected full-blown invasion.
Israeli forces also made limited ground incursions on Wednesday and Thursday.
"We've entered a new phase in the war," Israeli Defence Minister Yoav Gallant said in a video on Saturday.
"Last night, the ground in Gaza shook. We attacked above the ground and below the ground. We attacked terror operatives of all ranks in every location."
Gaza Civil Defence spokesman Mahmud Bassal told AFP "Hundreds of buildings and houses were destroyed and thousands of other homes were damaged."
Witnesses said most of the bombing was concentrated in the Jabaliya district of northern Gaza.
The strikes left wide craters in the streets and flattened many buildings in the area.
'Death is everywhere'
Hundreds of Hamas fighters crossed the Israeli border in vehicles, by air and sea on October 7, indiscriminately killing civilians in the streets, in their homes and at an outdoor rave party.
The unprecedented attack caught Israel off guard and exposed serious intelligence failings.
"The army entered the Gaza Strip and extended its operations" with tanks and artillery, Israeli military spokesman Daniel Hagari said on Saturday.
Israeli fighter jets hit 150 "terror tunnels, underground combat spaces and additional underground infrastructure" and "several Hamas terrorists were killed", the army said.
Hamas's armed wing, the Ezzedine al-Qassam Brigades, said it targeted Israeli forces in an area of northern Gaza near the border on Saturday.
Israeli warplanes flew overhead as booms were heard coming from Gaza, AFP journalists reported.
"There are a large number of martyrs and a large number of survivors under the rubble, and we cannot reach them," a Gaza civil defence official said.
"The stench of death is everywhere, in every neighbourhood, every street and every house," respiratory physician Raed al-Astal told AFP from Khan Yunis in southern Gaza.
'Profound fear'
The families of Israeli hostages held by Hamas demanded on Saturday an immediate government explanation about their fate after the army's intensified strikes.
The Hostages and Missing Families Forum, which represents some 229 people believed abducted by Hamas, said the war cabinet had failed to explain to relatives whether the ground operation endangered the captives' well-being.
"The families are worried about the fate of their loved ones... Every minute feels like eternity," the group said.
On Thursday, the Ezzedine al-Qassam Brigades said "almost 50" hostages had been killed in Israeli bombing since October 7. AFP could not immediately verify the figure.
In Tel Aviv, Yael Leviel said reading about the Israeli operations offered "support and strength" as "all of us continue to live in profound fear".
"We cannot afford to lower our guard... our very existence is at stake," the 50-year-old social worker told AFP.
Communications blackout
Hamas said all internet connections and communications across Gaza had been cut.
AFP journalists in Gaza confirmed they were only able to communicate in limited areas where they could connect to Israeli networks across the border.
Human Rights Watch warned the near-total telecommunications blackout in Gaza risked providing cover for "mass atrocities".
The Palestinian Red Crescent said the outage had disrupted ambulance services.
The UN humanitarian coordinator for the Palestinian territories, Lynne Hastings, said on X, formerly Twitter, that "hospitals & humanitarian operations can't continue without communications".
Between the bombardments and the fuel shortages, 12 of Gaza's 35 hospitals have been forced to close.
The UN agency for Palestinian refugees, UNRWA, said it has had to "significantly reduce its operations".
Israel's military accused Hamas of using hospitals in Gaza as operations centres for directing attacks, which Hamas denied.
'Stop this madness'
Turkish President Recep Tayyip Erdogan said "Israel must immediately stop this madness and end its attacks" in a post on X on Saturday after the UN General Assembly called for an "immediate humanitarian truce" in Gaza.
The non-binding resolution on Friday received overwhelming support, but Israel and the United States criticised it for failing to mention Hamas.
Israel's bombardment has displaced more than 1.4 million people inside Gaza, according to the UN, while supplies of food, water and power to the crowded territory have been almost completely cut off.
Israel has blocked all deliveries of fuel, saying it would be exploited by Hamas to manufacture weapons and explosives.
A first tranche of aid was allowed on October 21, but only 84 have crossed in total, according to the UN, which says a daily average of 500 trucks had entered Gaza before the conflict.
UNRWA chief Philippe Lazzarini said Gazans were "not only dying from bombs and strikes, soon many more will die from the consequences of (the) siege".
"These few trucks are nothing more than crumbs that will not make a difference."
Violence has also risen sharply in the occupied West Bank since the October 7 attacks, with more than 100 Palestinians killed and nearly 2,000 wounded, according to the UN.