Thousands of Palestinians were fleeing northern Gaza on Sunday after a night of intense Israeli strikes and an explicit warning from the army that the raids were set to intensify. 

In Beit Lahiya, whole streets were emptying, with residents fleeing with all the belongings they could carry -- by car, by donkey- and horse-drawn carts, and on foot. 

The world implored Israel and Hamas Saturday to end hostilities as warplanes pounded Gaza for a fifth straight day, killing at least 45 Palestinians, and militants replied with rockets.

Both sides have brushed off calls for a truce, and Israel is building up troops and armor on the Gaza border for a possible ground invasion.

The U.N. Security Council urged Israel and Hamas Saturday to end their hostilities in Gaza, calling on both sides to respect "international humanitarian laws" and stop the loss of life.

In a unanimous declaration, the 15-member council called for a deescalation of the crisis that has claimed well over a hundred lives, and urged a return to the "calm and restitution of the November 2012 ceasefire."

Twenty-year-old Palestinian Sally Saqr lies in a hospital bed in Gaza's Shifa hospital with burns that have turned her cheeks an angry pink beneath her ventilation tube.

She survived an Israeli strike in the early hours of Saturday morning that hit a care home for Palestinians with special needs.

British Foreign Secretary William Hague said he will discuss an international push for a ceasefire in Gaza with U.S. Secretary of State John Kerry and his German and French counterparts during talks in Vienna on Sunday.

Hague said in a statement on Saturday that the discussions on ending the hostilities between Israel and Gaza would take place on the sidelines of talks on Iran's nuclear program in the Austrian capital.

Iran's foreign minister has called for an "immediate end" to Israel's bombing of Gaza and criticized the United States for not restraining its most important Middle Eastern ally.

Mohammad Javad Zarif, in a taped interview with U.S. broadcaster NBC to air Sunday, urged Washington to use the United Nations to stop the Israeli strikes.

Egypt's President Abdel Fattah al-Sisi warned Saturday that escalating the conflict between Israel and Hamas in Gaza would cost more "innocent lives," as the death toll climbed to 127 Palestinians.

Sisi's spokesman said the government was in touch with both sides after the president met Mideast Quartet envoy Tony Blair in Cairo.

Speaker Nabih Berri stated on Saturday that the resistance is the only response to Israeli atrocities, noting that the “national Palestinian unity will remain the strongest and the lasting weapon” in the face of violence.

"The only response to the massacre and to the violence is the resistance which is the people's sole weapon to deter atrocities,” Berri said on the eve of the July 2006 war with Israel.

The music video opens with Palestinian Hamas fighters in fatigues building, transporting and then firing rockets at Israel -- but the triumphant lyrics are being sung in Hebrew, not Arabic.

"We prepare a generation of warriors who cling to death like the enemy clings to life," the words run, with Arabic subtitles.

Arab foreign ministers are to meet in Cairo on Monday to discuss the escalating conflict between Hamas militants in Gaza and Israel which has already killed more than 120 Palestinians, a diplomat said.

Kuwait, which holds the rotating leadership of the Arab League headquartered in the Egyptian capital, had demanded the "urgent" meeting, the diplomat told AFP on Saturday.