GAZA CITY, Gaza Strip — Israeli soldiers shot and killed at least 52 Palestinians during mass protests along the Gaza border on Monday. It was the deadliest day there since a devastating 2014 cross-border war and cast a shadow over Israel's festive inauguration of the new US Embassy in contested Jerusalem.

In a show of anger fueled by the embassy move, protesters set tires on fire, sending plumes of black smoke into the air, and hurled firebombs and stones toward Israeli troops across the border. Later on Monday, Israeli forces fired from tanks, sending protesters fleeing to take cover.

The military said its troops came under fire in some areas, and said protesters tried to break through the border fence. It said troops shot and killed three Palestinians trying to plant a bomb.

President Donald Trump said in a video message played at the embassy inauguration — which took place just 70 kilometers (45 kilometers) from the bloodshed on the Gaza border — that he remains committed to "facilitating a lasting peace agreement" between Israelis and Palestinians.

"A great day for Israel!" Trump tweeted earlier Monday.

However, Monday's steadily climbing death toll and wall-to-wall condemnation of the embassy move by the Arab world raised new doubts about Trump's ambitions to broker what he once said would be the Mideast "deal of the century."By late afternoon, at least 52 Palestinians, including five minors, were killed, the Gaza Health Ministry said. One of the minors was identified as a girl.

The ministry said 1,204 Palestinians were shot and wounded, including 116 who were in serious or critical condition.

The statement says about 1,200 others suffered other types of injuries, including from tear gas.

At the embassy ceremony in Jerusalem, Trump son-in-law and chief Mideast adviser Jared Kushner placed the blame on the Gaza protesters.

"As we have seen from the protests of the last month and even today those provoking violence are part of the problem and not part of the solution," he said.

Kushner and Trump daughter Ivanka led a high-powered American delegation that also included the treasury secretary and four Republican senators.

The new embassy will temporarily operate from an existing US consulate, until a decision has been made on a permanent location.

In Gaza, the Hamas-led protest was meant to be the biggest yet in a weeks-long campaign against a decade-old blockade of the territory. The Israeli military estimated a turnout of about 40,000, saying this fell short of what Hamas had hoped for.

The march was also directed at the inauguration of the embassy.

Moving the embassy from Tel Aviv to Jerusalem — a key Trump campaign promise — infuriated the Palestinians, who seek east Jerusalem as a future capital.

Monday marked the biggest showdown in years between Israel's military and Gaza's Hamas rulers along the volatile border. The sides have largely observed a cease-fire since the 2014 war — their third in a decade.