Israel-Gaza updates: Israel says ground operation underway in southern Gaza

The United States will send three relief flights into Egypt on Tuesday to keep up the flow of humanitarian aid into the war-torn Gaza Strip, which has reached its highest levels as officials take advantage of the current humanitarian pause.

"The movement over the last four or five days of assistance has been so significant in volume that a backfill in El Arish [International Airport in Egypt] is now needed, and these planes are part of that backfill," a senior Biden administration official told reporters during a telephone call on Monday afternoon.

Some 800 trucks carrying aid have crossed into Gaza during the first days of the pause, officials said, which is a huge increase from the days prior. So far, a total of about 2,000 aid trucks have entered Gaza since Oct. 7, meaning that 40% of them had gone in in just the last four days.

The planes on Tuesday will be carrying medical aid urgently needed in Gaza as well as food, particularly for children, and winter clothing as the rainy season begins, according to officials.

The aid will be delivered by the United Nations to civilians.

Two more planeloads are expected to follow in the coming days, officials said. Previously, there were also five commercial flights of aid coordinated by the U.S. government, according to officials.

The officials emphasized this aid as part of U.S. President Joe Biden’s commitment to helping the Palestinian people, saying that he has made sure America is the largest single donor both to the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) and to Palestinian territories.

Going forward, the officials said the goals for humanitarian aid in Gaza will be expanding access, pushing for restoration of essential services, especially water, and keeping civilians out of harms way.

"The president has also consistently stressed the importance of ensuring military operations are conducted in a manner consistent with international humanitarian law, including with respect to the protection of civilians," the senior Biden administration official told reporters.

Officials did not offer any new information on the hostage negotiations between Gaza's militant rulers, Hamas, and Israel but reiterated that they hope to see Americans released in the coming days.

-ABC News' Cheyenne Haslett and Morgan Winsor

The 11 former hostages who were released by Hamas on Monday are all in stable condition following an initial medical evaluation, Prof. Dror Mandel, Director of Dana-Dwek Children's Hospital at Ichilov Medical Center in Tel Aviv, Israel, told media early Tuesday morning local time.

Mandel said staff will continue to conduct medical evaluations of the nine children and two mothers, who are currently spending time with their families "in a quiet environment."

In Gaza, where the humanitarian crisis is worsening by the day, 68% of the people killed are women and children, while four out of five residents are displaced, according to U.N. Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Martin Griffiths.

"I don't think I've seen anything like this before. It's complete and utter carnage," he told CNN on Sunday.

"Nobody goes to school in Gaza. Nobody knows what their future is. Hospitals have become a place of war, not of curing," Griffiths said.

"It's not just a crisis about Gaza. It's a crisis about humanity," Griffiths said. "War has become the option of the day, and the suffering that comes from it is astronomical."

Eleven more hostages who were abducted from Israel on Oct. 7 have been released and are in the custody of the Red Cross, an Israeli Defense Forces spokesperson said.

The 11 hostages released from Gaza Monday were dual citizens -- from Israel as well as France, Germany and Argentina -- while the 33 released Palestinians are comprised of 30 minors and three women, Qatari officials said.

Israel identified the returned hostages as 12-year-old Eitan Yahalomi, 51-year-old Karina Engel-Bart, 18-year-old Mika Engel, 12-year-old Yuval Engel, 34-year-old Sharon Aloni-Cunio, 3-year-old Yuli Cunio, 3-year-old Emma Cunio, 16-year-old Sahar Calderon, 12-year-old Erez Calderon, 16-year-old Or Yaakov and 12-year-old Yagil Yaakov.

8:35

11 more hostages released from Gaza in exchange for 33 PalestiniansSixty-nine hostages have been released by Hamas, exchanged for 150 Palestinians released from Israeli prisons.

ABCNews.com