Amid the slaughter, President Donald Trump's top aides and supporters are
celebrating the occasion. Trump's daughter Ivanka and son-in-law Jared Kushner,
along with U.S. Treasury Secretary Steve Mnuchin were leading the ceremonies.
It was the highest Palestinian death toll in a single day since a series of protests dubbed the "Great March of Return" began near the fence on March 30, and since the 2014 Gaza war.
The health officials said 900 Palestinians were wounded, about 450 of them by live bullets.
According to the Palestinian envoy to the UN, Israeli fire claimed the lives of eight children under the age of 16.
"We condemn in the strongest terms these atrocities by the Israeli occupying forces, using this massive fire power against civilians who have the right to demonstrate peacefully - and they have been demonstrating peacefully," Ambassador Riyad Mansour said.
Tens of thousands streamed to the site on Monday as clouds of black smoke from tires set alight by demonstrators rose in the air.
"Today is the big day when we will cross the fence and tell Israel and the world we will not accept being occupied forever," said Gaza science teacher Ali, who declined to give his last name.
"Many may get martyred today, so many, but the world will hear our message. Occupation must end," he said.
"A great day for Israel," the U.S. president, who stoked Arab anger by recognizing disputed Jerusalem Al-Quds as Israel's so-called capital in December, said in a tweet.
Turkey said the United States shared responsibility with the occupying regime of Israel for the "massacre".
"The U.S. administration is as responsible as the Israeli government for this massacre," Deputy Prime Minister Bekir Bozdag wrote on Twitter, saying the incidents were caused by "unjust and unlawful decisions".
Iran's Foreign Minister Muhammad Javad Zarif lashed out at the Israeli regime for pursuing a repressive approach toward peaceful protests.
"Israeli regime massacres countless Palestinians in cold blood as they protest in world's largest open air prison. Meanwhile, Trump celebrates move of U.S. illegal embassy and his Arab collaborators move to divert attention. A day of great shame,” he wrote on Twitter.
The Arab League will hold an extraordinary meeting to discuss the United States’ "illegal" move of embassy to Al-Quds, state news agency MENA reported Monday, citing an Arab diplomat.
MENA said the meeting will be held Wednesday at the level of permanent representatives to the Arab League "to counter the illegal decision taken by the United States of America to transfer its embassy to Al-Quds".
Hundreds of people protested outside the new United States embassy in Jerusalem Al-Quds, with many in the crowd waving Palestinian flags and shouting "Free Palestine!”
The 52 Palestinian dead on Monday included a 14-year-old boy, a medic and a man in a wheelchair who had been pictured on social media using a slingshot.
The latest casualties raised the Palestinian death toll to more than 100 since the protests started six weeks ago. No Zionist casualties have been reported.
At the protest sites, families sat in the shade of tents nearly 800 meters from the border fence. Hundreds of protesters ventured to within several hundred meters of the barrier, while others moved even closer, rolling burning tires and hurling stones.
Some flew flaming kites to try and torch bushes on the other side of the fence and distract Israeli marksmen. Hundreds of Palestinians were treated for tear gas inhalation.
The killings have drawn international criticism, but the United States has supported the occupying regime.
More than 2 million people are crammed into the narrow strip, which is blockaded by Egypt and the occupying regime of Israel.
Hardline Zionist education minister Naftali Bennett told Israel Radio that the regime would treat the Gaza fence as an "Iron Wall" and anyone who approached it as a "terrorist".
Palestinian Prime Minister Rami Hamdallah, in a statement on Monday, accused the United States of "blatant violations of international law".
The protests are scheduled to culminate on Tuesday, the day Palestinians mourn as the "Nakba" or "Catastrophe" when, in 1948, hundreds of thousands of them were driven out of their homes or fled the fighting around Israel's creation.
"Choosing a tragic day in Palestinian history (to open the embassy) shows great insensibility and disrespect for the core principles of the peace process," Hamdallah wrote.
The Russian government said it feared the embassy move would increase tensions across the Middle East.