BEIRUT — Israel battled militants on two fronts Wednesday, pursuing a ground incursion into Lebanon against Hezbollah that left eight Israeli soldiers dead and conducting strikes in Gaza that killed dozens, including children. As Israel vowed to retaliate for Iran’s ballistic missile attack a day earlier, the region braced for further escalation.

Iran, which backs both Hezbollah and the Hamas militants who run the Palestinian enclave of the Gaza Strip, launched dozens of missiles into Israel on Tuesday night, a sharp escalation that pushed the Middle East closer toward a regional war.

Israel warned that the attack would have “repercussions.”

The Israeli military said seven soldiers were killed in two separate attacks in southern Lebanon, without elaborating. Those deaths followed an earlier announcement of the first Israeli combat death in Lebanon since the start of the incursion — a 22-year-old captain in a commando brigade. Another seven troops were wounded.

Together, the assaults announced on the eve of Rosh Hashana, the Jewish new year, were some of the deadliest against Israeli forces in months.

In Gaza, where the nearly yearlong war that triggered the widening conflict rages 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 as well as the United States, which has rushed military assets to the region in support of Israel.

Syria’s state-run SANA news agency said an Israeli airstrike hit a residential building in Damascus on Wednesday evening, killing three people and wounding at least three others.

There was no immediate comment from Israel, which frequently hits targets linked to Iran or allied groups in Syria, but rarely claims the strikes.

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 killed militants in “close-range engagements,” without saying where.

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 two attacks announced Wednesday followed other assaults on Israeli forces earlier in the year.

In June, an explosion in southern Gaza killed eight Israeli soldiers. In January, 21 Israeli troops were killed in a single attack by Palestinian militants in central Gaza, the deadliest single attack on Israeli forces since the Israel- Hamas war erupted.

The Lebanese army said Israeli forces 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 and around 50 villages and towns to evacuate north of the Awali River, 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.

Israel has said it will continue striking 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.

Israeli strikes have killed more than 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, declaring Secretary-General António Guterres persona non grata, or banned from entering the country. Israeli Foreign Minister Israel Katz accused him of failing to unequivocally condemn Tuesday night’s Iranian missile attack.

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

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 showed 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.

Iran launched at least 180 missiles into Israel on Tuesday in what it said was retaliation for a series of devastating blows Israel landed recently against Hezbollah, which has been firing rockets into Israel since the war in Gaza began in solidarity with Hamas.

Israeli Prime Minister Benjamin Netanyahu vowed to retaliate, saying Iran “made a big mistake tonight and it will pay for it.”