At least 17 people were killed in an Israeli strike on a packed Gaza market Wednesday in a deadly raid that came as Israel was observing a four-hour humanitarian lull.
Thick black smoke billowed over the site in the war-torn Shejaiya neighbourhood as at least five ambulances raced to the scene where bodies lay strewn on the ground, an AFP correspondent said.
A bloodied, limp lifeless body lay in a pool of petrol and mud, his head crushed, one of at least 17 people who were killed. At least another 200 were wounded, medics said.
It was supposed to have been a rare pause for Gaza's battered population of 1.8 million to go out in safety to stock up on goods, and for medics to evacuate the dead and wounded.
Instead, there was further bloody mayhem with more than 30 people killed across Gaza in the first three hours of the lull alone, sending the death toll from 23 days of unrelenting Israeli attacks soaring to 1,336.
Israel had said its truce, which began at 1200 GMT, would not apply in places were troops were "currently operating," hours after the army made what it called a "significant advance" into the narrow coastal strip.
Hamas denounced the four-hour lull as a publicity stunt, saying it had "no value".
The strike on the market came hours after Israeli tank shells slammed into a UN school sheltering some 3,300 homeless Gazans, killing 16 and drawing a furious response from the United Nations.
"This morning a UN school sheltering thousands of Palestinian families suffered a reprehensible attack," UN chief Ban Ki-moon said on a visit to Costa Rica.
"It is unjustifiable, and demands accountability and justice."
The attack was also denounced by the White House in a carefully-worded statement which avoided mentioning Israel.
"The United States condemns the shelling of a UNRWA school in Gaza, which reportedly killed and injured innocent Palestinians, including children, and UN humanitarian workers," a statement said.
- 'End the carnage' -
"They're bombing houses, homes, schools -- there's no protection," said Moin al-Athamna, one of those who had been staying at the school when the attack occurred.
Inside one classroom, two young men wearing Palestinian boy scout scarves were engaged in the grisly task of collecting body parts. Their ungloved hands were stained with blood as they picked up chunks of flesh and put them into thin plastic bags.
"They were all kids in there, young people," said Hisham al-Masri. "Why would they do this? Where can people go?"
It was the second time in a week that a school run by the UN agency for Palestinian refugees had been hit, prompting a blistering attack on Israel by UNRWA Commissioner General Pierre Krahenbuhl.
"I condemn in the strongest possible terms this serious violation of international law by Israeli forces," he said, indicating the school's location in the Jabaliya camp had been communicated to the Israeli army 17 times.
"No words to adequately express my anger and indignation," he wrote on his official Twitter account, describing it as "intolerable."
Israeli tank shelling and air strikes killed 106 Palestinians and wounded hundreds more on Wednesday, medics said, hiking the overall toll to 1,336.
And in Israel, the army said three troops had been killed in Gaza, raising the overall number of soldiers killed to 56 since the operation began on July 8.
Situated on the Mediterranean coast, flanking Israel and Egypt, the Gaza Strip is home to 1.8 million Palestinians who live in an area of just 362 square kilometres (140 square miles).
It is one of the most densely populated areas in the world, a fact that was not lost on the influential British band Massive Attack.
"This bombardment of an area that is one of the most densely populated on earth, where civilians aren't allowed to leave, is just beyond belief," frontman Robert Del Naja told AFP in Lebanon where he dedicated the band's Middle East gig to the children of Gaza.
"In order to protect yourself, do you really want to massacre another people?" he asked in a question directed at Israel.
- Israeli team in Cairo  -
But there appeared to be no Israeli appetite for a truce, despite an hours-long meeting of the security cabinet, with a senior official telling Haaretz newspaper that the Jewish state wasn't even close to a ceasefire.
"When a cease-fire proposal that answers Israel's important needs is laid on the table, it will be considered," he said, warning the military operation would expand.
"The operation continues and the IDF (army) will expand its attacks against Hamas and the rest of the terror organisations."
Despite the rhetoric, a two-member Israeli delegation arrived in Cairo late on Wednesday to discuss a possible ceasefire with Egyptian officials, an official at the airport told AFP, saying they were expected to leave after several hours.
An Israeli official also confirmed a defence ministry team had left for the Egyptian capital, without giving further details.
Cairo, a key mediator in previous truce negotiations between Israel and Hamas, was also expected to host a Palestinian delegation later this week.