The world implored Israel and Hamas to end hostilities Saturday, but the violence escalated with Israel widening its range of Gaza bombings and rockets continued to be launched from the Strip towards Israel.
Saturday was the bloodiest day since the conflict erupted on Tuesday, with at least 52 Palestinians killed.
With the Palestinian death toll reached at least 154, and with no Israelis killed, the UN Security Council unanimously urged Israel and Hamas to respect "international humanitarian laws" and stop the loss of life.
The 15-member council urged a return to "calm, and restitution of the November 2012 ceasefire", referring to Gaza's last deadly full-scale conflict.
On Friday, the United Nations said 77 percent of those killed in the Israeli raids were civilians.
Al Jazeera's Stefanie Dekker, reporting from Al-Shifa hospital in Gaza City, said medical facilities in the territory were overwhelmed.
"Most of the casualties we are seeing here are, overwhelmingly, civilians. It really is a horrendous scene," she said. People are absolutely terrified. The hospitals are having issues with the lack of materials to deal with the people coming in."
Both sides have dismissed calls for a truce, and Israel continued to build up troops along the Gaza border ahead of a possible ground invasion, warning Palestinians in northern Gaza to evacuate their homes.
Handicapped centre bomb
Israel's aerial campaign - the largest and deadliest since 2012 - saw strikes start early on Saturday, including one that hit a centre for the handicapped, and another that killed two nephews of Gaza's former premier, Ismail Haniya.
One of the women killed had cerebral palsy and the other suffered severe mental handicaps. Among the three wounded patients were a quadriplegic, one with cerebral palsy and one with mental disabilities, she said.
Later on Saturday night, an Israeli strike hit the Tuffah district in eastern Gaza City, targeting a home and a mosque and killing at least 16 people, medics said.
Among the wounded was police chief Tayseer al-Batsh, officials said.
Hamas fired rockets after issuing a warning that it planned to fire at the Israeli city of Tel Aviv.
Three rockets apparently targeting Jerusalem fell short, hitting Hebron and Bethlehem, the Israeli army and Palestinian security sources said, with no reports of casualties.
Of four fired at Tel Aviv, three were intercepted above the city and another hit open ground south of it, the army said.
Over 500 projectiles have struck Israel during the conflict, but none have resulted in Israeli deaths.
More Israeli strikes
Israel's chief military spokesman, Motti Almoz, said on Saturday there would be more strikes, especially in northern Gaza near the Israeli border.
"We are going to attack there with great force in the next 24 hours due to a very large concentration of Hamas efforts in that area," he said.
Late on Saturday, the military said it was ordering Palestinians in northern Gaza to evacuate "for their own safety."
In a sign that the conflict might widen, Israel fired into Lebanon late on Saturday after two rockets were fired from there into northern Israel.
Amid international efforts to mediate a truce, Egyptian president Abdel Fatah el-Sisi's government was in touch with both sides, his spokesman said.
Sisi met Middle East Quartet envoy Tony Blair in Cairo on Saturday to discuss the crisis, and later warned any escalation would cause further loss of innocent lives.
Washington has said it is willing to "leverage" its relationships in the region to bring about a ceasefire.
The chief diplomats of Britain, France, Germany and the United States are due to discuss how to achieve a truce when they meet in Vienna on Sunday.