The fiercest fighting of the 13-day war in Gaza erupted yesterday as Israel dramatically widened its ground offensive, sending tanks and troops into urban areas and causing thousands of panicked civilians to flee.
The Palestinian government has described the attack on Gaza's Shejaiya neighbourhood, in which at least 60 people were killed, as a "war crime" which required immediate international intervention.
"The Palestinian consensus government condemned in the strongest terms the heinous massacre committed by the Israeli occupation forces against innocent Palestinian civilians in the neighbourhood of Shejaiya," a statement said.
The office of Palestinian president Mahmoud Abbas issued a similar statement condemning the "massacre".
The death toll in Gaza has hit at least 425 since the July 8 start of Israel's military offensive there, with 87 killed yesterday alone, Palestinian health officials said.
The vast majority of yesterday's dead were in the Shejaiya neighbourhood between Gaza City and the Israeli border, with at least 62 people killed there in a blistering bombardment which began overnight, emergency services spokesman Ashraf al-Qudra said.
Following an urgent appeal from the International Committee of the Red Cross, both sides agreed to temporarily halt fire in the neighbourhood, ending at 1730 GMT.
As the ceasefire got under way, a convoy of ambulances entered Shejaiya, with medics seen picking up at least three dead bodies, including that of a man with his intestines hanging out and his head destroyed, an AFP correspondent reported.
Al-Qudra said that of the 425 Palestinians killed since the start of Israel's Operation Protective Edge, 112 were minors, 41 women and 25 elderly people.
Images of the corpses of women and children lying in streets were posted on Facebook as hospitals were overwhelmed with the dead, injured and those seeking sanctuary from the onslaught.
Palestinian human rights organisations also warned that the disproportionate number of civilian deaths could constitute a war crime committed by Israel.
Despite Israel saying it had agreed to a two-hour ceasefire in the middle of the day, requested by the Red Cross to allow for the injured and dead to be evacuated, shelling and gunfire continued. Israel blamed continued Hamas rocket fire for the breakdown of the humanitarian truce.
All morning, terrified people ran from their homes, some barefoot and nearly all empty-handed. Others crowded on the backs of trucks or rode on the bonnets of cars in a desperate attempt to flee. Sky News reported that some had described a "massacre" in Shejaiya. Witnesses reported hearing small arms fire inside Gaza, suggesting gun battles on the streets. Heavy shelling continued from the air and sea.
Bodies were pulled from rubble amid massive destruction of buildings in the neighbourhood. Masked gunmen were on the streets.
Yesterday evening, Israeli forces had hit eastern areas of Gaza City with the heaviest bombardment yet of the 13-day war. The assault was most intense in the direction of Shejaiya, where an orange glow of flames lit up the sky. At one stage, artillery and mortar rounds were hitting the outskirts of the city every five seconds. Later in the night jets flew low passes over the coast.
The Guardian saw families squeezing into the back of what few vehicles were available as streets further east were pounded by artillery fire.
Columns of people, many of them too scared, angry and shocked to speak, approached down the main road to the east and from side streets, even as small arms fire was audible in the distance.
One of those fleeing was Sabreen Hattad, 34, with her three children. "The Israeli shells were hitting the house. We stayed the night because we were so scared but about six in the morning we decided to escape," she said.
"But where are we supposed to go? The ambulances could not enter and so we ran under shell fire."
Three other men pass by in a hurry clutching bedding in their arms. Asked what they had seen they would only answer: "Death and horror."
Many of those escaping Shejaiya made for Gaza's central Shifa hospital, which was engulfed by chaotic scenes and ambulances ferrying the dead came in a steady steam – among them a local TV cameraman, Khaled Hamad, killed during the overnight offensive, wheeled out wrapped in a bloody plastic shroud.
Those who had fled congregated in corridors, on stairs and in the hospital car park. Staff put mattresses on floors to accommodate the injured, while some patients were being evacuated.
Aish Ijla, 38, whose leg was broken by shrapnel, said: "We live very close to the border. When the shells started we couldn't leave the house. It is two storeys. The shells were hitting the upper floor so we all moved downstairs. There were 30 of us in the house. Then the shrapnel started hitting the door.
"It was quiet for a moment and we decided to run. But as we were on the road a shell landed near me, breaking my leg. I told the family to go on without me and carried on going for a little bit and stopping then going on. Eventually an ambulance reached me after two hours."
The UN agency for Palestinian refugees, UNRWA, said more than 63,000 people had sought sanctuary in 49 shelters it was providing in Gaza, and it expected the numbers to rise. "The number has tripled in the last three days, reflecting the intensity of the conflict and the inordinate threats the fighting is posing to civilians. We call on all sides to exercise maximum restraint and to adhere to obligations under international law to protect civilians and humanitarian workers," said spokesman Chris Gunness.
An Israeli air strike on the house of senior Hamas official Khalil al-Hayya killed his son and daughter-in-law and two children, hospital officials said. Near the southern town of Rafah shelling killed four Palestinians, according to officials.
Israel sent more troops into Gaza overnight after demolishing more than a dozen Hamas tunnels and intensifying tank fire on border areas. Israel disclosed that at least four soldiers had been killed in its ground offensive, and that more than two dozen wounded soldiers were evacuated to hospitals. There were unconfirmed reports that Israel suffered significant military casualties in a cross-border attack by Hamas militants yesterday morning.
Lieutenant Colonel Peter Lerner of the Israel Defence Forces said additional troops had been sent into Gaza on the orders of the government. "Forces have undergone an intensified training and thorough planning period and are prepared and stand ready for the task at hand," he said.
The Israeli military was setting up a field hospital to treat injured Palestinians at Erez, the northern border crossing between Gaza and Israel.
As fighting raged, the UN secretary general, Ban Ki-moon, headed to Qatar on Sunday as part of renewed ceasefire efforts. He was due to meet Mahmoud Abbas in Doha.
Abbas was also expected to meet Khaled Meshaal, the Hamas leader based in the Qatari capital.
Meanwhile, according to the Egyptian newspaper Ahram, the US secretary of state, John Kerry, was travelling to Cairo to aid the mediation effort.
Hamas last week rejected an Egyptian call to both sides to halt hostilities, insisting on advance guarantees that Israel and Egypt will significantly ease their border blockade of Gaza. Qatar has presented a ceasefire proposal incorporating Hamas's demands, while Egypt said on Saturday it had no plans to revise its ceasefire proposal.
Israel is opposed to Qatar's involvement, and insists that Egypt must be a party to any deal. Doha hosts a large number of exiled Islamists from across the Middle East, including Meshaal.
The French foreign minister, Laurent Fabius, who flew to Israel after meetings in Egypt and Jordan, said on Saturday efforts to secure a ceasefire had failed. "Sadly I can say that the call for a ceasefire has not been heard, and on the contrary, there's a risk of more civilian casualties that worries us," he said after talks with the Israeli prime minister, Benjamin Netanyahu.