JERUSALEM--Palestinians scrambled to flee northern Gaza after Israel's military ordered about 1 million people to leave for the territory's south ahead of an expected ground invasion following the surprise attack a week ago by the ruling Hamas militant group — despite warnings from the U.N. that evacuating nearly half of Gaza's population would be calamitous.

Families in cars, trucks and donkey carts packed with their possessions crowded a main road heading southward from Gaza City as Israeli airstrikes continued to hammer the besieged territory. Hamas’ media office said warplanes struck cars fleeing south, killing more than 70 people.

The Israeli military said its troops conducted temporary raids into Gaza to battle militants and hunted for traces of some 150 people abducted in Hamas’s shocking Oct. 7 assault on Israel.

In urging the evacuation, Israel’s military said it planned to target underground Hamas hideouts around Gaza City. But Palestinians and some Egyptian officials fear that Israel ultimately hopes to push Gaza’s people out through the southern border with Egypt.

The U.N. called on Israel to reverse the unprecedented directive.

Hamas told people to ignore the evacuation order. Families in Gaza faced what they saw as a no-win decision to leave or stay, with no safe ground anywhere. Israeli strikes have leveled entire city blocks, and Gaza has been sealed off from food, water and medical supplies — all under a virtual total power blackout.

“Forget about food, forget about electricity, forget about fuel. The only concern now is just if you’ll make it, if you’re going to live,” said Nebal Farsakh, a spokesperson for the Palestinian Red Crescent in Gaza City, as she broke into heaving sobs.

The Gaza Health Ministry said Friday that roughly 1,900 people have been killed in the territory. The Hamas assault killed more than 1,300 Israelis, most of whom were civilians, and roughly 1,500 Hamas militants were killed during the fighting, the Israeli government said.

Israel's raids into Gaza Friday was the first word of troops entering the territory since Israel began its round-the-clock bombardment in retaliation for Hamas’ massacre of hundreds of civilians in southern Israel.

A military spokesman said Israeli ground troops left after conducting the raids. The troop movements did not appear to be the beginning of an expected ground invasion.

No decision on a ground offensive has been announced, although Israel has been massing troops along the Gaza border.

An assault into densely populated and impoverished Gaza would likely bring even higher casualties on both sides in brutal house-to-house fighting.

“We will destroy Hamas,” Israeli Prime Minister Benjamin Netanyahu vowed Friday night.

Hamas said Israel’s airstrikes killed 13 hostages. It said the dead included foreigners but did not give their nationalities. Israeli military spokesperson Rear Adm. Daniel Hagari denied the claim.

In Israel, the public remained in shock over the Hamas rampage and frightened by continual rocket fire out of Gaza. Residents are overwhelmingly in favor of a military offensive, and Israeli TV stations have set up special broadcasts with slogans like “together we will win” and “strong together.” Their reports focus heavily on the aftermath of the Hamas attack and stories of heroism and national unity, and they make scant mention of the unfolding crisis in Gaza.

Israeli residents are in shock over the Hamas rampage and frightened by continual rocket fire out of Gaza.

In the occupied West Bank, the Palestinian Health Ministry reported 16 Palestinians were killed Friday, bringing the total of Palestinians killed there to 51. The U.N. says attacks by Israeli settlers have surged there since the Hamas assault.

The U.N. said the Israeli military's call for civilians to move south affects 1.1 million people. If carried out, that would mean the territory’s entire population would have to cram into the southern half of the 40-kilometer (25-mile) strip.

An Israeli spokesperson, Jonathan Conricus, said the military would take “extensive efforts to avoid harming civilians” and that residents would be allowed to return when the war is over.

Israel has long accused Hamas of using Palestinians as human shields. Israeli Defense Minister Yoav Gallant said Israel wanted to separate Hamas militants from the civilian population.

“So those who want to save their life, please go south,” he said at a news conference Friday with U.S. Defense Secretary Lloyd Austin.

U.N. spokesperson Stephane Dujarric said it would be impossible to stage such an evacuation without “devastating humanitarian consequences.”

Hamas’ media office said airstrikes hit cars in three locations as they headed south from Gaza City, killing 70 people. There was no immediate comment from the Israeli military.

Two witnesses reported a strike on fleeing cars near the town of Deir el-Balah, south of the evacuation zone and in the area Israel told people to flee to. Fayza Hamoudi said she and her family were driving from their home in the north when the strike hit some distance ahead on the road and two vehicles burst into flames. A witness from another car on the road gave a similar account.

“Why should we trust that they’re trying to keep us safe?” Hamoudi said, her voice choking. “They are sick.”

Many feared they would not be able to return or would be gradually displaced to Egypt’s Sinai Peninsula.

More than half of the Palestinians in Gaza are descendants of refugees from the 1948 war surrounding Israel’s creation, when hundreds of thousands fled or were expelled from what is now Israel. For many, the evacuation order dredged up fears of a second expulsion. Already, at least 423,000 people — nearly 1 in 5 Gazans — have been forced from their homes by Israeli airstrikes, the U.N. said Thursday.

“Where is the sense of security in Gaza? Is this what Hamas is offering us?” said one resident, Tarek Mraish, standing by an avenue as vehicles flowed by.

The U.N. estimated that tens of thousands had fled homes in the north by Friday night.

Gaza’s Health Ministry said it was impossible to safely transport the wounded from hospitals, which are already struggling with high numbers of dead and injured. “We cannot evacuate hospitals and leave the wounded and sick to die,” spokesperson Ashraf al-Qidra said.

Farsakh, of the Palestinian Red Crescent, said some medics refused to abandon patients and instead called colleagues to say goodbye.

“We have wounded, we have elderly, we have children who are in hospitals,” she said.

Al Awda Hospital struggled to evacuate dozens of patients and staff after the military contacted it and told it to do so by Friday night, said the aid group Doctors Without Borders, which supports the facility. The military extended the deadline to Saturday morning, it said.

The U.N. agency for Palestinian refugees, known as UNRWA, said it would not evacuate its schools, where hundreds of thousands have taken shelter. But it relocated its headquarters to southern Gaza, according to spokesperson Juliette Touma.

“The scale and speed of the unfolding humanitarian crisis is bone-chilling. Gaza is fast becoming a hellhole and is on the brink of collapse,” said Philippe Lazzarini, UNRWA’s commissioner general.