Fleeing Palestinians are facing fear and uncertainty after the Israeli military told all residents north of Wadi Gaza -- 1.1 million people -- to evacuate their homes within 24 hours and move south.

The Israeli Defense Forces made the announcement on Friday morning because it plans to "operate significantly in Gaza City in the coming days" to target Hamas and wanted "to avoid harming civilians."

Afaf Al-Najjar, a 21-year-old university student, told ABC News she woke up to the announcement in a hotel where she had been staying with her parents. From there, she says they waited for two hours to get a cab home to pick up important documents such as their passports, ID cards, and birth certificates, along with some clothes.

Al-Najjar said they finally made it to her grandparents' home in Khan Yunis, a city in southern Gaza. Along with her immediate family, the families of her cousin and two uncles are also sheltering at her grandparents' home.

Still, she worries it's also not safe in the new location.

"We realized that the airstrikes were happening in Khan Yunis as well. Very heavy ones. Just a couple of minutes ago, there was one that shook the entire house. Obviously, the night is going to be dreadful, as always. And we still don't know what is going to happen," Al-Najjar said.

Hamas told civilians to stay put, prompting Israel and the U.S. to accuse the militant group of wanting to use civilians as human shields.

The IDF said in social media posts that it believes Hamas terrorists are hiding in Gaza City, including in buildings with "innocent civilians" inside.

"Those who want to save their life, please go south. We are going to destroy Hamas infrastructures, Hamas headquarters, Hamas military," Israeli Defense Minister Yoav Gallant said Friday.

Jason Shawa, an English-Arabic translator and father of two, says he fled northern Gaza to his small cottage in central Gaza, where he is hosting a total of 41 people.

"Everybody has been instructed by the Israeli army to leave or face death. So we chose to leave. Of course, we left," Shawa said.

"We're getting by and just hoping it blows over. And we hope we stay safe," he added.

United Nations Secretary-General António Guterres briefly addressed the evacuation while speaking to reporters on Friday afternoon, saying it was "extremely dangerous, and in some cases, simply not possible."

"Moving more than 1 million people across a densely populated war zone to a place with no food, water or accommodation, where the entire territory is under siege, is extremely dangerous, and in some cases, simply not possible," Guterres said, speaking at the U.N. headquarters in New York.

He warned that "hospitals in the south of Gaza are already at capacity and will not be able to accept thousands of new patients from the north."

After the announcement, the U.N. Agency for Palestine Refugees relocated its central operation center and international staff to southern Gaza, the UNRWA said in a post on X early Friday morning local time.

Doctors Without Borders issued a statement Friday calling the Israeli government's 24-hour notice to leave northern Gaza "outrageous."

The World Health Organization called on Israel to immediately reverse its evacuation order, saying "a mass evacuation would be disastrous for patients, health workers and other civilians left behind or caught in the mass movement."

Seventy people were killed and 200 were injured in an Israeli strike on a convoy of civilians heading from northern Gaza to central Gaza, according to the Palestinian government press office.

The death toll has continued to mount on both sides since Hamas launched a surprise incursion into Israel on Saturday, prompting Israeli forces to retaliate.

In Israel, more than 1,300 people have died, and 3,227 others have been injured, according to Israeli officials. An estimated 100 to 150 hostages are currently being held by Hamas in the Gaza Strip.

In Gaza, at least 1,799 people have died, including 583 children and 351 women, officials said. Another 7,388 people were injured.