The death toll more than doubled the number of Palestinians killed during six weeks of demonstrations, dubbed the "March of Return," and came on the same day that a new U.S. Embassy opened in Jerusalem.
Tens of thousands of Palestinians had gathered on the edges of the fenced off blockaded territory from mid-morning. Many came to peacefully demonstrate, bringing their children, carrying flags. Food stalls sold snacks and music blared.
But the protests appeared to have a more violent edge than in previous weeks. Some young men brought knives and fence cutters. At a gathering point east of Gaza City, organizers urged protestors over loudspeakers to burst through the fence, telling them Israeli soldiers were fleeing their positions, even as they were reinforcing them.
Israeli snipers were determined not to allow a breach, and ambulances soon began screaming back and forth from the fence, as gunshots rang out over the crowd. No Israeli soldiers were injured, though, and Israel drew widespread condemnation for an excessive use of force.
More than 2,700 people were injured, according to the Palestinian health ministry in Gaza, including 1,359 from live ammunition. The dead included six children under the age of 18, among them a 15-year-old girl, and a medic, the ministry said.
The United Nations said that "those responsible for outrageous human rights violations must be held to account," and Human Rights Watch described the killings as a "bloodbath." Palestinian Authority President Mahmoud Abbas condemned a continuing "massacre" of the Palestinian people. Both Turkey and South Africa announced they were recalling their ambassadors from Israel.
The Trump administration, however, blamed Hamas for the loss of life. "The responsibility for these tragic deaths rests squarely with Hamas," deputy White House press secretary Raj Shah told reporters at a briefing. "Israel has the right to defend itself."
The violence was jarring contrast with the opening ceremony for the embassy in Jerusalem, which drew first daughter Ivanka Trump and her husband Jared Kushner.
Palestinians mark that day - known as the "nakba" or "catastrophe" - on Tuesday, when more demonstrations are planned. More than two-thirds of Gaza's population is descended from refugees who were displaced at the time of Israel's creation.
At Gaza City's main al-Shifaa hospital, medics said they were overwhelmed.
"I don't know how we will manage," said Ayman al-Sahbani, the head of the emergency department, as families jostled to get in to see injured relatives. "How long can this go on? How long?"
The hospital had set up a new additional 30-bed triage area outside, and earlier in the day said it had the capacity to treat 200 or 300 serious gunshot wounds. It had received around 400 injured by around 6.pm., and most of those had been shot, he said.
"We've reached the critical point now," he said. "A lot of people need operations soon, but the operation room is full."
Increasing economic hardship has fuelled frustrations in Gaza, along with wider despair across Palestinian territories amid moves by a U.S. administration seen as wholeheartedly on Israel's side of the decades-old conflict.
At least 110 Gazans have been killed over the past six weeks, according to health ministry figures. At the demonstrations east of Gaza, some said the force used by Israel would only bring further unrest.
Standing a few hundred meters from the fence, Nirma Attalah, 29, said her 22-year-old brother had been killed two weeks ago. "My brother was shot in the head in this place," she said. She had come on Monday with her whole extended family. "We are here for Jerusalem, for Palestinian land," she said.
A truck rolled past carrying young men chanting: "To Jerusalem we go with millions of martyrs" and "Death rather than humiliation."
Drones dropped canisters of tear gas sending crowds fleeing. Other drones dropped leaflets, urging demonstrators to say back from the fence.
"People have come out of the rubble to say we will not forget our rights," said Yousef Abu Saleh, 25. "The American administration is adopting the Israeli story and stealing our right of return."
While some said they would abide by official calls to keep the demonstrations peaceful, others talked about their enthusiasm to break into Israel and wreak havoc.
Two other young men carried large knives and said they wanted to kill Jews on the other side of the fence.
The Israeli military brought in two extra brigades to the Gaza border in preparation for the demonstrations and added additional "defense lines" in an effort to prevent any mass invasion into Israeli communities near the border.
The military said at least 40,000 people protested in 13 different places along the fence - more than twice as many locations as in past weeks of protest.
"Especially violent riots" took place near the southern Gazan city of Rafah,where three people were killed after trying to plant an explosive, the military added. The military also said it would "act forcefully against any terrorist activity," and it carried out an airstrike on Hamas military posts in northern Gaza after Israeli troops came under fire.
At demonstrations near the Bureij Camp in central Gaza, Ahmed Loulou, 22, released a cluster of balloons carrying a Palestinian flag. In marker he'd written: "We are returning. This is our land." The load was briefly caught in a power line before bobbing unsteadily towards the border.
He said it was his first time at the demonstrations and had been persuaded to come by friends.
Meanwhile, young men launched stones from slingshots as they sheltered behind earthen berms. Shortly afterwards, the sound of live ammunition zinged through the air over the sound of the afternoon call to prayer.
"Sniper! Sniper!" shouted a young boy.
The vast majority of demonstrators were unarmed, but near a parking area, a man pulled out an AK-47 and took aim at an Israeli drone dropping leaflets. He let off a stream of bullets into the air and brought it down. Later, more gunfire ensued as different Palestinian factions argued who would keep the downed drown, onlookers said.
As the death toll neared 50, loudspeakers called for protesters to leave the border area. Hamas leader Ismail Haniya was called to Cairo on Sunday night in an apparent attempt to persuade the militant group to quell the demonstrations. No agreement was made, said Hamas spokesman Taher al-Nounou, as he attended the protests. "They understood our points. Our people are showing their solidarity with Jerusalem today, and showing their anger with the U.S. administration."
Hamas' Interior Ministry said seven of its members were killed, including a medic from the civil defense, two internal security staff, and military intelligence official. At least 12 journalists were injured, according to the health ministry.
The demonstrations have proved to be a welcome distraction for Hamas, refocusing anger against Israel as frustration built against the group in Gaza.
In a press conference as evening fell, senior Hamas official Khalil al-Hayaa, said the protests would continue.
"This blood will keep boiling until the occupation leaves forever," he said.
At a morgue, the blood was washed off the bodies of those killed before they were taken away by waiting relatives. Dressed in a blue Chelsea soccer shirt, Ahmed Jundiya, 20, was waiting for the body of his 20-year-old cousin. Jundiya himself hadn't been at the demonstrations.
"I wanted to go but my parents said 'no,' " he said. "You can see the result of participating," he added, motioning towards the room where his relative lay.
The Washington Post's Anne Gearan in Washington and Sufian Taha in Jerusalem contributed.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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