Israel on Thursday imposed a full siege on the Gaza Strip, vowing there would be "no humanitarian exceptions" to the blockade until all hostages captured by Hamas were freed.
The comments came after humanitarian groups on the ground pleaded for fuel to be allowed in to prevent overwhelmed hospitals from "turning into morgues".
Gaza's sole electric power station has ceased operation and hospitals are running out of fuel for emergency generators.
Israel launched a deadly air campaign against the besieged territory- home to 2.3 million people, mostly children - killing over 1.400 Palestinians and wounding more than 6,000.
The onslaught came after Hamas fighters broke through the Israeli blockade on Saturday and carried out attacks inside Israel that left 1,300 people dead. Scores of Israeli hostages were taken back to Gaza, including soldiers.
Israel's fierce and indiscriminate bombing has destroyed civilian infrastructure and flattened entire neighbourhoods.
The International Committee of the Red Cross (ICRC) said fuel powering emergency generators at hospitals could run out within hours.
"The human misery caused by this escalation is abhorrent, and I implore the sides to reduce the suffering of civilians," ICRC regional director Fabrizio Carboni said on Thursday.
"As Gaza loses power, hospitals lose power, putting newborns in incubators and elderly patients on oxygen at risk. Kidney dialysis stops, and X-rays can’t be taken. Without electricity, hospitals risk turning into morgues."
However, Israel's Energy Minister Israel Katz said there would be no exceptions to the siege, posting on X, formerly known as Twitter: "Humanitarian aid to Gaza? No electrical switch will be lifted, no water hydrant will be opened and no fuel truck will enter until the Israeli hostages are returned home. Humanitarian for humanitarian. And nobody should preach us morals."
What is a total siege?
Gaza Strip, a 140-square-mile area, home to 2.3 million Palestinians - mostly children, relies on Israel for power, the supply of fuel, food and basic services.
"No power, no food, no gas," Israel's Defence Minister Yoav Gallant said of the total siege announced against the impoverished and already-besieged enclave.
Gaza gets its power from its sole power plant, which is operated by inefficient diesel fuel, which enters Gaza from the Kerem Shalom crossing with Israel. Some electricity is also supplied through Israel's electricity company.
Cutting off fuel and power from the territory could leave many civilians without power, which will exacerbate a lack of potable water if there is not enough power for the territory's desalination plants to operate. No power also means no drinking water, proper sanitation or health care.
On Wednesday, Palestinian authorities said Gaza's only power plant has run out of fuel and stopped operating, according to The New Arab's correspondent in Gaza.
The full siege may also result in a "severe shortage of already scarce drinkable water", the United Nations has warned.
"A humanitarian crisis is unfolding before our eyes," Chiara Saccardi, Action Against Hunger's spokesperson for Gaza told TNA.
"The imposed blockade and lack of safe humanitarian corridors have left Gaza without electricity. This affects access to water, communications, food, health services and the most basic needs," Saccardi said.
"The widespread, deliberate and disproportionate targeting of civilians by any party is contrary to international humanitarian law, as is the collective punishment of civilian populations," she warned, adding that Israel's actions were "fuelling a catastrophic humanitarian crisis and removing any prospect of a solution to this crisis."
How is this different from the previous siege on Gaza?
The humanitarian crisis that Palestinians have endured in Gaza in the past has been severe even before this latest war, and now it will get much worse.
Gaza has been described as living under siege for over 16 years, as documented by United Nations experts and human rights groups.
Israel and Egypt control all of the impoverished enclave's border crossings, and Israel controls its access to the Mediterranean Sea and airspace.
Israel has restricted and closely monitored movement in and out of the enclave, imposing shutdowns during previous wars, including Israel's aerial military campaigns in 2008 and 2014, which killed at least 3,500 Palestinians, including dozens of children.
Israel and Egypt have never allowed enough construction materials into the border crossings under their control to enable Gaza’s rebuilding after conflicts.
The impoverished enclave has extreme rates of poverty, with over 60 percent of Palestinians needing food assistance.
Access to health care is also extremely limited, with many having to wait for permits to allow them to cross into Israel for treatment. About a quarter of Palestinians in Gaza, and nearly 80 percent of youth, are unemployed.
The UN previously described the blockade on Gaza as "collective punishment".
How is the world responding?
Rights groups have called for an immediate cessation of the "indiscriminate bloodshed" and the establishment of safe spaces and safe passage for people to reach.
The medical charity Médecins Sans Frontières - Doctors Without Borders (MSF) said essential humanitarian supplies like medicine, medical equipment, food, fuel and water must also be allowed to enter the Gaza enclave.
It called for the reopening of Egypt's Rafah border crossing, which was hit by an Israeli strike earlier this week.
"The fighter jets are demolishing entire streets block by block," Matthias Kennes, MSF Head of Mission in Gaza, told TNA.
"There is no place to hide, no time to rest. Some places are being bombed on consecutive nights. We know what it was like in 2014 and in 2021, thousands died," Kennes said.
"Each time our medical colleagues go to work, not knowing if they will see their homes or their families again. But they say this is different. This time, after five days, there have already been 1,200 deaths. What can people do? Where are they supposed to go?"
Relief organisations like the World Food Programme and Mercy Corps have called for humanitarian corridors "to facilitate the entry of critical supplies like medicine, food, and water".
United Nations Secretary-General António Guterres has condemned the siege.
"The humanitarian situation in Gaza was extremely dire before these hostilities; now it will only deteriorate exponentially," he said in a statement.