Médecins Sans Frontières (Doctors Without Borders) and the World Health Organization released updates on a deteriorating situation in Gaza, imploring for an immediate cease-fire to allow aid to enter and civilians to take shelter.

The MSF is seeing a "complete collapse" in the healthcare system in Gaza, the organization said. It has been 10 days since MSF was forced to stop providing support to Martyrs and Beni Suheila clinics due to the Israeli forces’ evacuation orders for the area, according to the statement.

In Rafah, on the southernmost area of the Gaza Strip and where people from Khan Younis and central Gaza have been pushed to, health services are extremely limited, according to MSF.

"The United Nations Security Council must demand an immediate and sustained ceasefire, to lift the siege and ensure unrestricted aid to the entire Gaza Strip," the MSF statement read.

Meanwhile, according to the WHO, a mission it conducted with partners to deliver essential trauma and surgical supplies to Al-Ahli hospital to cover the needs of 1500 people, and to transfer 19 critical patients, was successful.

The high-risk delivery was managed despite active shelling and artillery fire in the region, according to a statement from the organization.

The hospital itself has been substantially damaged, and in acute need of oxygen and essential medical supplies, water, food and fuel as well as medical personal, the WHO said.

"We cannot wait any longer for a sustained ceasefire and a safe, scaled-up humanitarian response," WHO officials said in a statement.

-ABC News' Will Gretzky

Since the end of the cease-fire on Dec. 1, the Israeli Air Force has struck 3,500 targets in the Gaza Strip, Israel Defense Forces confirmed to ABC News on Sunday.

Many of the targets hit by the IAF were identified by IDF forces on the ground, IDF officials said in a statement.

Since beginning of the war, more than 22,000 "terror targets" have been struck in the Gaza Strip, according to the IDF.

Among the targets hit by the Israeli forces are ones in Jabalya, Shejaiya, Beit Hanoun and Khan Yunis, the IDF said. Troops are also conducting raids on Hamas terrorist strongholds across the Gaza Strip, according to the IDF.

Numerous terrorists have been killed in the raids and terrorist infrastructure has been destroyed, according to the IDF.

Additionally, IDF naval troops are operating off the coast of the Gaza Strip, striking terror targets from the sea and supporting IDF ground troops, according to the IDF.

-ABC News' Jordana Miller

The Biden administration approved the possible sale of tank ammunition to Israel through an emergency order, circumventing Congress.

In a release, the State Department notified Congress about the emergency sale on Friday.

"The Secretary of State determined and provided detailed justification to Congress that an emergency exists that requires the immediate sale to the Government of Israel of the above defense articles and services in the national security interests of the United States, thereby waiving the Congressional review requirements under Section 36(b) of the Arms Export Control Act, as amended," the release states.

The sale -- of 120mm tank cartridges and related equipment -- is estimated to cost $106.5 million.

-ABC News' Davone Morales and Shannon Crawford

All ships bound for Israel, notwithstanding their nationality, will be stopped from passing through the Red Sea and become "a legitimate target" until more aid is delivered to Gaza on these ships, a Yemeni Armed Forces spokesperson said.

"The Yemeni armed forces announce the prohibition of the passage of ships bound for the Zionist entity of any nationality, if they do not enter the Gaza Strip with the food and medicine they need and it will become a legitimate target for our armed forces," according to a statement.

As the death toll continues to climb, UNICEF called the Gaza Strip the most dangerous place in the world for children.

"The Gaza Strip is the most dangerous place in the world to be a child. Scores of children are reportedly being killed and injured on a daily basis. Entire neighborhoods, where children used to play and go to school have been turned into stacks of rubble, with no life in them," UNICEF said in a statement.

Close to 1 million children in Gaza have been "forcibly displaced from their homes," according to UNICEF.

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Gaza Strip is the most dangerous place to be a child: UNICEF

"They are now being pushed further and further south into tiny, overcrowded areas without water, food, or protection, putting them at increased risk of respiratory infections and waterborne disease. Their lives are further threatened by dehydration, malnutrition and disease," UNICEF said.

"UNICEF and other humanitarian actors have been ringing the alarm for weeks. Our team on the ground describe meeting children with missing limbs and third-degree burns, and children left shell-shocked by the continuing violence that surrounds them," UNICEF said.

UNICEF called for an immediate ceasefire.

"An immediate, long-lasting humanitarian ceasefire is the only way to end the killing and injuring of children, the only way that civilians can be protected, and the only way to enable the urgent delivery of desperately needed lifesaving aid," UNICEF said.