The last planned U.S. charter flight out of Tel Aviv's Ben Gurion Airport is set for Tuesday, according to the State Department.

"Commercial availability remains limited out of Ben Gurion Airport," the State Department said. "Please go to Ben Gurion International Airport, Terminal 3 if you wish to depart Israel. U.S. Embassy personnel will be present to direct you and provide specific flight information. Be prepared to wait."

State Department spokesperson Matt Miller said the chartered flights are ending because there's no longer enough American passengers to fill them.

"It is purely a demand issue. We had a charter flight yesterday that had five people on it," he said Monday. "We've consistently seen the demand for our charter flights go down to where we had a lot of flights going out with 50% capability. I think the number of seats that we have offered, we have had something like 25% of that actually be filled."

"We have notified everyone that the charter flight tomorrow is the last one that we are currently planning, so if they do want to leave, now's the time to do it," he continued. "But we will always conduct assessments in real time about whether there's additional demand, whether circumstances change on the ground, and if we need to make additional arrangements, we will of course be open to doing so."

State Department spokesperson Matt Miller said Hamas was making "a number of demands" for opening the Rafah border crossing between Egypt and Gaza to foreign nationals, including the 500 to 600 Americans who are trapped in Gaza.

"Hamas is making a number of demands before they’ll allow people to leave Gaza. I’m not going to speak to those demands, but it's something we're continuing to try to work through," he said.

-ABC News' Shannon Crawford

State Department spokesperson Matt Miller claimed Monday that the U.S. was making "significant progress" on getting fuel into Gaza via a "reliable delivery mechanism" that would assuage Israel's fear that it could be intercepted by Hamas.

"Fuel is essential to the delivery of humanitarian assistance, the desalinization of water and the provision of medical care and we want to see it provided for those purposes as soon as possible," Miller said. "I should note that even as we work to provide fuel for these essential humanitarian services, Hamas continues to maintain extensive fuel reserves. Rather than provide that fuel to hospitals or aid workers or for other civilian needs, however, it continues to hoard it for the benefit of its fighters and to carry out its terrorist attacks against Israel."

-ABC News' Shannon Crawford

Twenty-six more aid trucks entered Gaza through the Egypt-Gaza Rafah border crossing on Monday, Egyptian state TV reported.

The humanitarian crisis in Gaza has worsened by the day, with residents trapped without food, water, electricity and internet as Israeli strikes continue.

A total of 150 trucks have entered Gaza, according to State Department spokesperson Matt Miller.

"We aim to surpass that number today, tomorrow and beyond," Miller said Monday.

Doctors Without Borders called for a ceasefire Saturday saying the conflict has reached "a new low in an endless stream of unconscionable violence." The organization, which has been providing medical care to people in Gaza, also condemned world leaders for not calling for a ceasefire.

"The deadly attack outside the gate of Al-Shifa hospital impacting an ambulance is horrendous. This is a lethal attack outside Gaza's main and busiest hospital, where our staff work daily to provide lifesaving medical care. We have repeatedly called for an immediate and total ceasefire, for the protection of healthcare facilities, as well as medics, patients and people who are taking shelter there," Doctors Without Borders said in a statement Saturday.

"This is a new low in an endless stream of unconscionable violence. The repeated strikes on hospitals, ambulances, densely populated areas and refugee camps are disgraceful. How many people have to die before world leaders wake up and call for a ceasefire?" Doctors Without Borders said.

This comes as the Palestinian death toll rises to 9,488 -- including 3,900 children and 3,509 women -- and 24,158 Palestinians were injured, according to the Hamas-run Gaza Health Ministry.

One physician described seeing an ambulance hit outside Al-Shifa hospital.

"We were standing inside the hospital gate when the ambulance was directly hit in front of us. There were bloody bodies everywhere. Many were killed immediately, while we rushed others to the operating room for emergency care," Dr. Obaid, a Doctors Without Borders doctor at Al Shifa hospital, said.

The Israel Defense Forces claimed its aircraft hit an ambulance that it believes was being used by Hamas and called for civilians to move south for safety.

-ABC News' Cindy Smith and Emma Ogao