Israeli troops and tanks briefly raided northern Gaza overnight into Thursday, the military said, striking several militant targets in order to "prepare the battlefield" before a widely expected ground invasion after more than two weeks of devastating airstrikes.

The raid came after the UN warned that's it's on the verge of running out of fuel in the Gaza Strip, forcing it to sharply curtail relief efforts.

Gaza has been under a brutal siege — running out of food, water and medicine — since Hamas' bloody rampage across southern Israel earlier this month ignited the war.

The rising death toll in Gaza is unprecedented in the decades-long Israeli-Palestinian conflict.

The Health Ministry in Hamas-ruled Gaza said Thursday more than 7,000 Palestinians have died in the conflict, a figure that could not be independently verified.

Even greater loss of life could come if Israel launches an ground offensive aimed at crushing Hamas, which has ruled Gaza since 2007 and survived four previous wars with Israel.

Israeli airstrikes in the southern city of Khan Younis levelled more than eight homes belonging to an extended family, killing at least 15 people. Ambulances raced to the scene as dust from the collapsing buildings hung in the air.

The blast zone was a chaotic wasteland of crumbled concrete and twisted metal. Rescuers carried wounded people covered in gray dust.

The body of a boy was dug out from beneath a concrete slab, where his head had come to rest next to the foot of another person entombed in the wreckage.

The Israeli military says it only strikes militant targets and accuses Hamas of operating among civilians in densely-populated Gaza.

Palestinian militants have fired rocket barrages into Israel since the war began. One struck a residential building in the central city of Petah Tikva, without wounding anyone.

The conflict has threatened to ignite a wider war across the region. Hezbollah, an Iranian-funded ally of Hamas operating out of Lebanon, has repeatedly traded fire with Israel along the border. Israel has carried out airstrikes in Lebanon, Syria and even the occupied West Bank.

Israel has vowed to crush Hamas' capacity to govern Gaza or threaten Israel again, while also saying it doesn't want to reoccupy the territory from which it withdrew soldiers and settlers in 2005.

That could prove a daunting challenge, since Hamas is deeply rooted in Palestinian society, with political and charity organizations as well as a formidable armed wing.

Benny Gantz, a retired general and a member of Israel's war Cabinet, said any possible ground offensive would be only "one stage in a long-term process that includes security, political and social aspects that will take years.”

“The campaign will soon ramp up with greater force," he added.

During the overnight raid, soldiers killed fighters and destroyed militant infrastructure and anti-tank missile launching positions, the military said.

It said that no Israelis were wounded. There was no immediate confirmation of any Palestinian casualties.

Israeli Rear Adm. Daniel Hagari, a military spokesman, said the limited incursion was “part of our preparations for the next stages of the war.”

Israel also said it had also carried out around 250 airstrikes across Gaza in the last 24 hours, targeting tunnel shafts, rocket launchers and other militant infrastructure.

The Gaza Health Ministry says more than 7,000 Palestinians have been killed in the war — a figure that includes the disputed toll from an explosion at a hospital.

That is more than three times the number of Palestinians killed in the six-week-long Gaza war in 2014. The ministry's toll includes more than 2,900 minors and more than 1,500 women.

On Wednesday, the wife, son, daughter and grandson of Wael Dahdouh, a veteran Al-Jazeera correspondent in Gaza, were killed in an Israeli strike.

Dahdouh and other mourners attended the funerals on Thursday wearing the blue flak jackets used by reporters in the Palestinian territories.

The fighting has killed more than 1,400 people in Israel, mostly civilians slain during the initial Hamas attack, according to the Israeli government. Hamas also holds at least 224 hostages in Gaza.

The warning by the UN agency for Palestinian refugees, UNRWA, over depleting fuel supplies raised alarm that the humanitarian crisis could quickly worsen.

Gaza's population has also been running out of food, water and medicine. About 1.4 million of Gaza's 2.3 million residents have fled their homes, with nearly half of them crowded into UN shelters.

Hundreds of thousands remain in northern Gaza, despite Israel ordering them to evacuate to the south, saying those who remain might be considered “accomplices” of Hamas.

In recent days, Israel has let more than 70 trucks with aid enter from Egypt, which aid workers say is insufficient and only a tiny fraction of what was being brought in before the war.

Israel is still barring deliveries of fuel — needed to power generators — saying it believes that Hamas will take it.

“This is a small amount of what is required, a drop in the ocean,” said William Schomburg, an official with the International Committee of the Red Cross in Gaza. “We are trying to establish a pipeline.”

UNRWA has been sharing its own fuel supplies so that trucks can distribute aid, bakeries can feed people in shelters, water can be desalinated, and hospitals can keep incubators, life support machines and other vital equipment working.

If it continues doing all of that, fuel will run out by Thursday, so the agency is deciding how to ration its supply, UNRWA spokeswoman Tamara Alrifai told The Associated Press.

More than half of Gaza's primary health care facilities and roughly a third of its hospitals have stopped functioning, the World Health Organisation said.

At Gaza City's al-Shifa Hospital, the lack of medicine and clean water have led to “alarming” infection rates, the group Doctors Without Borders said. Amputations are often required to prevent infection from spreading in the wounded, it said.

Hamas' surprise attack on October 7 in southern Israel stunned the country with its brutality, its unprecedented toll and the failure of intelligence agencies to know it was coming.

Israeli Prime Minister Benjamin Netanyahu said in a speech Wednesday night that he will be held accountable, but only after Hamas was defeated.

“We will get to the bottom of what happened," he said.