U.S. Secretary of State Antony Blinken is set to meet with Jordan’s King Abdullah on Saturday and will join a meeting of foreign ministers of five Arab countries, also attended by a representative of the Palestinian Authority led by Mahmoud Abbas.

The prime objective of the talks is to ease Gaza’s growing humanitarian crisis, but that mission is complicated by Israel's insistence there can be no temporary cease-fire until all hostages held by Hamas are released. Israel has also presented the argument that a cease-fire would be in Hamas’s favor.

Meanwhile, U.N. Secretary-General Antonio Guterres has again called for an immediate cease-fire to allow humanitarian aid into the Gaza Strip, saying the conditions in Gaza are now "horrific" with food and water needed along with fuel for generators that power hospitals.

The U.N.’s director for Palestinian refugees says that the average Gaza inhabitant is living on two pieces of bread made from flour the UN had stockpiled and that people in southern Gaza have been forced to do all their washing on the beach using seawater as clean water runs out.

Thirteen people were killed and 26 were injured from a blast that struck ambulances at the gate of Gaza's Al-Shifa hospital complex, according to the Hamas-run Gaza Health Ministry.

The Palestinian Red Crescent Society said the group of ambulances were returning to the hospital from a mission to transport injured people to the Gaza-Egypt Rafah border crossing.

The Israel Defense Forces said its aircraft hit an ambulance that it believes was being used by Hamas.

"We have information which demonstrates that Hamas' method of operation is to transfer terror operatives and weapons in ambulances," the IDF said.

"A number" of Hamas terrorists were killed in the blast, the IDF said.

The IDF said, "We emphasize that this area is a battle zone. Civilians in the area are repeatedly called upon to evacuate southwards for their own safety."

The U.S. Embassy in Cairo helped more than 100 U.S. citizens and family members who left Gaza for Egypt on Thursday, according to the White House. "Another large group of Americans" is expected to leave Gaza on Friday, the White House said.

The U.S. is aware of more Americans and family members who left Gaza on Thursday and didn't seek out help from the embassy in Cairo, White House press secretary Karine Jean-Pierre said.

-ABC News' Justin Ryan Gomez

Ramy ElNazer, CEO of the Egyptian Red Crescent, warned Friday that the organization is about to run out of its stock of humanitarian aid to send to Gaza.