Gaza's Hamas-run Ministry of Health said the health sector in Gaza was "in a state of complete collapse" on Monday, as three major hospitals, including the enclave's largest medical center, Al Shifa Hospital, all went "out of service." At Al Shifa, dozens of babies requiring intensive care were at grave risk after their incubators shut off due to lack of electricity, the ministry said.

"Aluminum foil is kept around the babies to protect them from the cold weather," Mehdat Abbas, director general of the Hamas-run Ministry of Health, told CBS News. "It's becoming winter and the weather is becoming colder now. For that reason, without having proper temperature for them, they immediately die. I hope — I hope — that they will remain alive despite the disaster this hospital is passing through."

World Health Organization Director-General Dr. Tedros Adhanom Ghebreyesus said in a statement on Sunday that the situation was "dire and perilous," and that "the constant gunfire and bombings in the area have exacerbated the already critical circumstances." He said the number of patient fatalities had tragically increased, and called for a ceasefire.

"The world cannot stand silent while hospitals, which should be safe havens, are transformed into scenes of death, devastation, and despair," he said.

Israel said that it would transfer babies in need of intensive care from Al Shifa to another, safer hospital, but the nonprofit Medical Aid for Palestinians, which said it had been supporting the neonatal unit at Al Shifa for years, disputed that such a transfer would be possible.

"With ambulances unable to reach the hospital — particularly those with the skills and equipment needed to transfer these babies — and no hospital with capacity to receive them, there is no indication of how this can be done safely," Melanie Ward, CEO of Medical Aid for Palestinians, said in a statement. "The only safe option to save these babies would be for Israel to cease its assault and besiegement of Al Shifa, to allow fuel to reach the hospital, and to ensure that the surviving parents of these babies can be reunited with them."

The Israeli army, which had surrounded the Al Shifa compound on Monday, says Hamas is using the hospital as a base, and that Hamas complexes lie under the hospital compound, which the group denies. The Israeli claim is a possible prelude to a direct attack on the facility. Under international law, hospitals are protected during wartime, unless they are "misused," when they can become legitimate targets. 

Al Shifa was already in crisis after more than a week of Israeli bombardment around the facility. Outside, bodies of the dead were numbered and laid on the street. Without anesthesia or light, doctors carried on trying to help patients inside.

Israel's military said it tried to deliver 80 gallons of fuel to power the generators at Al Shifa, but it says Hamas prevented a pickup. The hospital director said that amount of fuel would only have been enough for between 15 and 30 minutes of power for the hospital.

"History will judge us," the U.N. head for Humanitarian Affairs in the Occupied Palestinian Territories, Andrea de Domenico, told CBS News. "[The Israel Defense Forces] have to balance out the military advantage with precaution. Even when the need is justifiable, then you have to make any effort possible to protect civilians," de Domenico said.

Most who could still move south in Gaza were trying to do so. Hundreds of thousands had already evacuated from the north of the enclave, including a 6-hour old baby with her grandmother. It was a "journey of torment," the grandmother said, as the child's mother was left behind.

Meanwhile, Israel's military was pushing deeper south. At one refugee camp, Israeli troops displayed what they said were Hamas weapons being stored there, and further evidence that civilians are being used as human shields, a violation of international law.

"Both parties have the obligation to respect international humanitarian law," Andrea de Domenico from the U.N. said. "Nobody, in reality, is taking care of civilians."

Emmet Lyons contributed to this report.