The Israeli government announced Wednesday there will be 50,000 additional reserve soldiers in preparation for possible escalation on the Lebanon front.

The announcement, made on Israeli Army Radio, came on the same day as Israeli Prime Minister Benjamin Netanyahu's visit to the northern border.

Netanyahu said Israel is "prepared for a very strong action in the north."

-ABC News' Ellie Kaufman

At least 18 suspects were arrested on suspicion of "violent crimes, assault and threats and disorderly conduct at the annual march to mark Jerusalem Day," according to Israeli Police.

The march of flags continues into the Old City and the Western Wall as thousands of Jerusalem District police officers, police reinforcements, MGB fighters and volunteers work in the various missions and sectors. The Israeli Police said it is working throughout Jerusalem to secure the tens of thousands of participants, maintain order and direct traffic on Jerusalem Day.

The march left a trail of violence as it kicked off in the early afternoon of Wednesday. Predominantly right-wing Israeli ultra-nationalists attended, many very young, marching through Muslim areas of Jerusalem’s Old City and attacking local business owners and journalists.

Among those arrested were suspects of different ages involved in “various incidents of violence in the Old City, possession of a knife and threats towards police officers,” police said.

Some of the roads that were blocked were opened to traffic and the police continue to work to maintain security and order.

Al-Asima journalist Saif Al Qawasmi said he was attacked on duty and beaten on his head and hand, video shows.

Hareetz journalist Nir Hasson also said he was attacked by a group of Israeli nationalist youths and posted videos showing the violent scenes.

These protesters were consistently chanting racist slurs throughout their march and attacking people as filmed by witnesses and reported by an ABC News team on the ground.

The massive group of far-right Israelis marched into Jerusalem’s old city chanting, “Death to Arabs!” “May your village burn!” and “The nation is alive!"

Tensions were already high for this event, which draws thousands of people and all Palestinian shops were closed by the Israeli police.

-ABC News' Marcus Moore, Nasser Atta, Jordana Miller and Camila Alcini

Amid an escalation of fighting and bombing in Gaza, at least 70 are dead and over 300 wounded in the last 48 hours, according to Doctors Without Borders.

"We have seen hospitals being bombed. We have seen refugee camps being bombed. We have seen humanitarian warehouses being bombed. The situation is apocalyptic," Karin Huster, a Doctors Without Borders nurse, said in a statement Wednesday.

"While the Rafah crossing point remains closed, these repeated mass casualties incidents are bringing the health system to the point of collapse," Doctors Without Borders said in a statement.

Medical teams at Al-Aqsa hospital -- one of the only remaining functional health facilities in central Gaza -- have received a huge influx of patients, many of whom arrived with severe burns, shrapnel wounds, fractures and other traumatic injuries.

"The odor of blood in the hospital's emergency room this morning was unbearable. There are people lying everywhere, on the floor, outside... bodies were being brought in plastic bags. The situation is overwhelming," said Huster.

-ABC News’ Guy Davies

The U.S. continues to push Hamas to agree to the cease-fire proposal President Joe Biden outlined Friday, saying Hamas' stated opposition to the deal has yet to be officially transmitted.

"We've seen some public comments from Hamas officials, but we have not yet gotten an official response from Hamas to the Qataris, who are the mediator to whom Israel gave their proposal that was transmitted to Hamas," White House national security adviser Jake Sullivan told ABC's George Stephanopoulos on "Good Morning America" Wednesday.

"The ball is in Hamas's court," Sullivan continued. "Israel has accepted the proposal. The world has endorsed the proposal. Now it's time for Hamas to say yes to it."

Sullivan argued the latest multi-phase proposal is key to ending the war, returning hostages, and increasing the flow of aid into Gaza, while ensuring Israel's security and a better future for Palestinians.

"That's what's on offer," Sullivan said. "That's what Hamas needs to step up and take and we're awaiting to get their official response."

Asked whether Biden thinks Israeli Prime Minister Benjamin Netanyahu was prolonging the war for political gain — which he suggested in a Time magazine interview out Tuesday — Sullivan pointed to Biden's answer to a question Tuesday evening asking if Netanyahu was playing politics.

"I don't think so. He's trying to work out the serious problem he has," Biden said Tuesday.

"And from our perspective, we're not going to delve into Israeli politics," Sullivan added. "What we're going to do is focus on the fundamental task at hand, which is President Biden's effort to end this war, get the hostages home, make sure Israel's safe and make sure the Palestinian people have a decent future."

-ABC News' Fritz Farrow

Centrist Israeli minister Benny Gantz announced Sunday that he was resigning from the emergency government because of what he has described as a lack of a plan from Israeli Prime Minister Benjamin Netanyahu for the "day after" in Gaza.

During a televised news conference, Gantz announced he was resigning from the coalition government, taking with him his State Party and the seats it held in the Knesset. Netanyahu's coalition government will still retain a majority, but the move by Gantz is considered a major blow to the prime minister.

"Netanyahu is preventing us from progressing towards a true victory," Gantz said. "For this reason, we are leaving the emergency government today, with a heavy heart, yet wholeheartedly."

He also called on Netanyahu to set a date for elections.

Gantz was set to make the announcement on Saturday but called it off amid the news of an Israel Defense Forces operation in Gaza that led to the rescue of four Israeli hostages.

Gantz is a member of Israel’s three-member war Cabinet, which includes Netanyahu and Defense Minister Yoav Gallant.

On Saturday, Netanyahu appealed to Gantz on X, saying, "This is the time for unity and not for division. We must remain united within ourselves in the face of the great tasks before us. I call on Benny Gantz -- do not leave the emergency government. Don't give up on unity."

Following Gantz's resignation, Netanyahu released a statement on X, saying, "Israel is in an existential war on several fronts."

"Benny, this is not the time to abandon the campaign -- this is the time to join forces," Netanyahu said. "Citizens of Israel, we will continue until victory and the achievement of all the goals of the war, primarily the release of all our hostages and the elimination of Hamas."

Netanyahu added, "My door will remain open to any Zionist party that is ready to get under the stretcher and assist in bringing victory over our enemies and ensuring the safety of our citizens."

In May, Gantz issued an ultimatum to Netanyahu, saying he would resign if the prime minister did not approve a post-war plan by June 8, saying at the time, "While the Israeli soldiers show supreme bravery on the front, some of the men who sent them into battle behave with cowardice and irresponsibility."

-ABC News' Jordana Miller