As the impact of the Israel-Hamas war is felt around the world, the conflict is presenting new challenges for U.S. leaders. 

GAZA CITY — A humanitarian crisis is gripping Gaza as hundreds of thousands of displaced Palestinians flee to the south amid the Israeli military’s aerial bombardment in retaliation for Hamas’ brutal terrorist attack one week ago.

The Israel Defense Forces warned residents to evacuate from Gaza’s north — home of its largest population center, Gaza City — on Friday, and the deadline has passed.

After the surprise assault Oct. 7, Israel placed the territory under siege, cutting off basic utilities. Today, Gaza is almost out of clean water, food, fuel and medical supplies. There hasn’t been electricity in days, and its largest hospital, Al-Shifa, is now a shelter for 35,000 people, with men sleeping in the parking lot and women inside.

There is little safety even for those fleeing. An airstrike hit a convoy of people trying to head south on a road that was supposed to provide safe passage. Among the dead were children and women, lying in pools of blood near vehicles. Ambulances were also struck.

“We’re dying, and everyone is watching. Shame on you, all the Arab countries. We were told to leave, but where? Where to go?” said Heba Al Attar, who is leaving a United Nations-operated school, which is supposed to be a safe place. “They’re shelling people on the roads, too. Where are we to go?” 

More than 1,900 people have been killed in Gaza, and more than 7,600 have been injured.

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Americans have been saying goodbye to relatives who are answering the call to fight in Israel.

Reservist Nor Labe bought his ticket to Israel before the military called him up.

“There was no way that I was going to sit at home,” he said.

Andrew Silverman, who was visiting his family in Chicago, jumped on a flight to Israel upon being notified that his friend had been killed in the conflict. “From there, the rest of the day became about me trying to get on a flight back to Tel Aviv,” Silverman said. “I think people are really using this as an opportunity to come together and help each other.”

Zev Baryodin left his 1-year-old son and pregnant wife to serve in Israel. “He is doing his duty, and I am extremely proud of him,” his father said.

Most Israelis enter the military at 18. After serving for two to three years, soldiers are typically placed in the Israel Defense Forces reserves and can serve for decades.

Members of the IDF who live overseas are not required to return upon a call to fight.

But to some, including Josh Jacobson, "it just felt so weird to be in Boston when there is so much going on here. It is my duty as part of the collective nation of Israel to come back and help."

The USS Dwight D. Eisenhower Carrier Strike Group is headed from Norfolk, Virginia, to the Eastern Mediterranean, Defense Secretary Lloyd Austin said today, part of an effort to deter a widening war.

Austin said the carrier strike group will join the USS Gerald R. Ford Carrier Strike Group, which arrived earlier week.

The Eisenhower group includes a guided missile cruiser, two guided missile destroyers and nine aircraft squadrons, Austin said in a statement.

Biden this week issued a warning to other groups or countries about the conflict.

“Let me say again — to any country, any organization, anyone thinking of taking advantage of this situation, I have one word: Don’t. Don’t,” he said.

At the Human Rights Campaign dinner tonight, Biden said the Israel-Hamas war is “another reminder that hate never goes away.”

"A week ago we saw hate manifest in another way in the worst massacre of Jewish people since the Holocaust. More than 1,300 innocent lives lost in Israel, including at least 27 Americans," he said.  

"It’s yet another reminder that hate never goes away," he told the crowd. "It hides. It hides under the rocks."

ASHDOD, Israel — Israel’s military is conducting an all-out hunt for Yahya Sinwar, the leader of Hamas in Gaza and mastermind of the worst attack in Israel's history.

The IDF says he's its Osama bin Ladin.

“When they chose to go full front against Israel, they signed their own death warrants," IDF Lt. Col. Peter Lerner said.

HOLLYWOOD, Fla. — Nata Nagli was in the family’s South Florida home last week when she woke her 22-year-old son, David, and told him about the Hamas terrorist attack on her native Israel.

David was soon on his feet, she said, telling her, “Mom, I know you’re going to start crying now,” which she did.

“But there’s nothing that you can tell me that’s going to stop me from going. I need to join my unit,” he said, Nagli told NBC News.

David joined the Israel Defense Forces when he was 18 and is in the reserves. Israel has called up more than 300,000 reservists since Hamas launched its terrorist attacks. Israel’s prime minister declared war on Hamas and vowed to crush it.

David’s parents drove him to the airport last Saturday, the day he and the world learned of the Hamas attacks.

A long time ago, David gave his mother a box with a bug inside that says, “Love Bug.” Nagli gave her son the box back at the airport as they said goodbye.

“When he hugged me goodbye, he said, ‘Mom, I promise I’m going to bring the love bug back,’” she said. 

NEAR THE ISRAEL-GAZA BORDER — It’s a quarter to 2 a.m. in Israel. Along the northern section of the Israel-Gaza border, you can hear the buzz of drones and fighter jets overhead.

Tanks on flatbeds have driven along the road bedside us — headed in the direction of Gaza.

We haven’t seen rocket fire here in a few hours, but we are hearing artillery. In the last 45 minutes, we’ve heard the booms of artillery at least nine times.

An estimated 35,000 people have sought refuge at Gaza City's main hospital, Al-Shifa, with men seen camping in its parking lot and women and children staying inside.

It's one of three Gaza City hospitals under orders to evacuate.

Today, the World Health Organization condemned the evacuation orders, which it said would cover 22 hospitals and their more than 2,000 inpatients in northern Gaza.

It's "tantamount to a death sentence" for patients, the WHO said in a statement.