The Israeli army continued its ground operation in Gaza City, with 50,000 Palestinian civilians fleeing on Wednesday via a temporary evacuation corridor, which will reopen on Thursday.
After more than a month of intense bombardment, hundreds of thousands of people remain trapped in a "dire humanitarian situation" in urban battle zones without enough food and water, the United Nations said.
Broken palm trees, distorted road signs and twisted lampposts marked the ruins of what was once north Gaza's main arterial route, an AFP journalist saw while embedded with Israeli soldiers.
Israeli flags were flying over buildings at beach resorts in northern Gaza and there was little sign of any human presence amid the destruction.
The utter devastation came as Israel pressed an offensive launched in response to the Hamas resistance on October 7. Vowing to destroy Hamas, Israel retaliated with a relentless bombardment and ground invasion that the Hamas-run health ministry in Gaza says has killed more than 10,500 people, many of them children.
The intense combat and the densely-populated coastal territory being effectively sealed off have led to increasingly dire conditions for civilians.
Israeli Prime Minister Benjamin Netanyahu has repeatedly rejected a ceasefire unless the hostages Hamas holds in Gaza are released.
The United States has backed Israel's rejection of a ceasefire, and G7 foreign ministers in Japan said on Wednesday they supported "humanitarian pauses and corridors."
As the war intensifies, discussions on the possible future of Gaza once the conflict ends have also grown, after Netanyahu this week said that Israel would assume "overall security" of the territory.
Kirby said on Wednesday that it was plausible that "for at least some period of time" Israeli forces would remain in Gaza "to manage the immediate aftermath and security situation."
Israel seized Gaza in the 1967 Six-Day War and withdrew in 2005. Two years later, Hamas took control and Israel imposed a crippling blockade.
In the longer term, US Secretary of State Antony Blinken has suggested the Palestinian Authority -- which exercises limited autonomy only in parts of the occupied West Bank -- should retake control of Gaza.
"It must include Palestinian-led governance and Gaza unified with the West Bank under the Palestinian Authority," Blinken said on Wednesday, repeating the long-standing US call for a two-state solution.
But senior Hamas member Ezzat al-Reshq gave short shrift to the suggestion.
Israel has vowed to destroy Hamas, with its soldiers targeting their deep network of tunnels and underground bases, while air-dropping leaflets and sending text messages ordering civilians in northern Gaza to flee south.
The army said 50,000 people had fled their homes in the main battle zone of northern Gaza on Wednesday, a sharp increase in numbers from earlier this week, adding to the more than 1.5 million people already seeking safety in the south of the coastal strip.
