The Israeli military said Wednesday that seven soldiers were killed in combat in southern Lebanon, a day after it announced a ground incursion into that country.

In addition, the military reported the death of Captain Eitan Itzhak Oster, a 22-year-old team commander in the Egoz Commando Unit from Modi'in, according to local media.

Oster's death marked the first fatality in Israel's ground operation against Hezbollah in Lebanon. Oster was killed during clashes with Hezbollah fighters in a village in southern Lebanon.

Fighting between Israeli troops and Hezbollah militants is ongoing in southern Lebanon, both sides said in separate statements.

The announcement comes as Israel sends more troops and artillery to the border area.

Israeli troops battled Hezbollah militants inside Lebanon on Wednesday after launching what they say are limited ground operations there. The region, meanwhile, braced for further escalation as Israel vowed to retaliate for Iran's ballistic missile attack the day before.

In Gaza, where the nearly yearlong war that triggered the widening conflict rages on with no end in sight, Israeli ground and air operations in a hard-hit city killed at least 51 people, including women and children, Palestinian medical officials said.

Israel has continued to strike what it says are militant targets across Gaza nearly a year after Hamas' Oct. 7 attack ignited the war.

The escalation on multiple fronts has raised fears of a wider war in the Middle East that could further draw in Iran — which backs Hezbollah and Hamas — as well as the United States, which has rushed military assets to the region in support of Israel.

Hezbollah, widely seen as the most powerful armed group in the region, said its fighters clashed with Israeli troops in two places inside Lebanon near the border. The Israeli military said ground forces backed by airstrikes had killed militants in “close-range engagements” without saying where.

The military also announced that soldier — a 22-year-old captain in a commando brigade — was killed in combat in Lebanon, the first such death since the start of the latest operations.

Israeli media reported infantry and tank units operating in southern Lebanon after the military sent thousands of additional troops and artillery to the border.

The Lebanese army said Israeli forces had advanced some 400 yards across the border and withdrew “after a short period,” its first confirmation of the incursion.

The Israeli military has warned people in around 50 villages and towns to evacuate north of the Awali River, some 37 miles from the border and much farther than the northern edge of a U.N.-declared zone intended to serve as a buffer between Israel and Hezbollah after their 2006 war. Hundreds of thousands have already fled their homes as the conflict has intensified.

Israel has said it will continue to strike Hezbollah until it is safe for tens of thousands of its citizens displaced from homes near the Lebanon border to return. Hezbollah has vowed to keep firing rockets into Israel until there is a cease-fire in Gaza with Hamas.

Israeli strikes have killed over 1,000 people in Lebanon over the past two weeks, nearly a quarter of them women and children, according to the Health Ministry.

Meanwhile, Israel lashed out at the United Nations on Wednesday, declaring Secretary-General António Guterres persona non grata, or banned from entering the country. Foreign Minister Israel Katz accused him of failing to unequivocally condemn the Iranian attack.

Guterres had released a brief statement after the barrage that read: “I condemn the broadening of the Middle East conflict, with escalation after escalation. This must stop. We absolutely need a cease-fire.”

The move deepens an already wide rift between Israel and the United Nations.

The Health Ministry in Gaza said at least 51 people were killed and 82 wounded in the operation in Khan Younis that began early Wednesday. Records at the European Hospital show that seven women and 12 children, as young as 22 months old, were among those killed.

Another 23 people, including two children, were killed in separate strikes across Gaza, according to local hospitals.

The Israeli military did not immediately respond to a request for comment.

Residents said Israel had carried out heavy airstrikes as its ground forces staged an incursion into three neighborhoods in Khan Younis. Mahmoud al-Razd, who had four relatives among those killed, described heavy destruction and said first responders had struggled to reach destroyed homes.

"The explosions and shelling were massive,” he told The Associated Press. “Many people are thought to be under the rubble, and no one can retrieve them.”

Israel carried out a weekslong offensive earlier this year in Khan Younis that left much of Gaza's second largest city in ruins. Over the course of the war, Israeli forces have repeatedly returned to areas of Gaza as militants have regrouped.