As the war with Hamas escalates and the death toll in the conflict climbs, Israel has been slamming Gaza with airstrikes and preparing an anticipated ground invasion of the Palestinian territory in response to Hamas’ brutal weekend attack on Israeli civilians.

The Israel Defense Forces (IDF) issued a warning Friday to the hundreds of thousands of Gaza City residents to flee farther south in the Gaza Strip for their “own safety.” 

Separately, the United Nations said the IDF told it late Thursday night that the everyone in northern Gaza should evacuate south almost immediately, raising expectations that the likely Israeli invasion is imminent. A U.N. spokesperson told CBS News the world body “considers it impossible for such a movement to take place without devastating humanitarian consequences,” but Israeli U.N. Ambassador Gilad Erdan said the U.N. response “to Israel’s early warning to the residents of Gaza” was “shameful” and ignores the brutality of the attack on Israel.

In response, Hamas has called on Palestinians to stay put in their homes, according to The Associated Press.

“This is chaos, no one understands what to do,” the AP quotes Inas Hamdan, an officer at the U.N. Palestinian refugee agency in Gaza City as saying.

The U.S. State Department announced Thursday it is arranging evacuation flights to help Americans leave Israel. According to the U.N., there are about 1.1. million people who live in northern Gaza. A spokesperson

As of Friday morning local time, Israel’s military said Hamas’ attack killed more than 1,300 people, including at least 27 Americans, and left some 3,200 people wounded. Fourteen U.S. citizens are among the missing, National Security Council Coordinator for Strategic Communications John Kirby said.

At least 1,537 people in Gaza, including 447 children, have been killed by Israel’s retaliatory strikes, the Gaza Ministry of Health said, adding that more than 6,600 others were wounded. 

Meanwhile, U.S. Secretary of State Antony Blinken spoke from Israel on Thursday and U.S. Secretary of Defense Lloyd Austin arrived in Tel Aviv Friday.