An Israeli airstrike on an apartment building in northern Lebanon that killed at least 22 people needs to be independently investigated, the United Nations’ human rights office said Tuesday.

“We have real concerns with respect to … the laws of war,” Jeremy Laurence, a spokesperson for the U.N.'s human rights office said a day after the strike, as rescue workers searching through the rubble found more bodies and remains. Laurence said the U.N. had received credible reports that a dozen women and children were among the dead.

The Israeli military said it “struck a target belonging to the Hezbollah terrorist organization" and that it would look into reports of civilian deaths.

The apartment building hit in the airstrike was in the small village of Aito, in the country’s Christian heartland and far from Hezbollah’s main areas of influence in Lebanon's south and east. The strike was a shock to residents, and it exacerbated fears that Israel would expand its offensive deeper into Lebanon.

“I heard a loud noise, like a boom,” said Dany Alwan, who lives next door. “We ran outside, I saw the dust and the smoke and the rubble. There was a body here, another one there. It was a really ugly and painful scene.”

The three-story building had been rented out to the Hijazi family, which fled their home in the southern village of Aitaroun, according to Elie Alwan, Dany Alwan's brother and the building's owner. Some 1.2 million people have fled southern and eastern Lebanon, where the fighting between Israel and Hezbollah has been concentrated.

Read: Israeli strike in northern Lebanon kills at least 21 people

As rescue workers rummaged through the debris on Tuesday, they found the body of a child, and later a small leg and other remains that they put together in a white bag. The Lebanese military watched as a bulldozer cleared heaps of twisted steel, destroyed olive trees, and crushed rocks.

Hezbollah's acting leader vows to step up strikes against Israel

Earlier on Tuesday, the acting leader of Hezbollah said the militant group would fire rockets into more areas of Israel until it ceases its airstrikes and ends its ground invasion of Lebanon.

Naim Kassem said Hezbollah is focused on “hurting the enemy,” comments made in a pre-recorded televised speech delivered on the same day the United States said it sent a small team of troops to Israel to support an American-made missile-defense system.

Hezbollah has fired thousands of rockets into Israel over the past year in support of Hamas' war with Israel in Gaza. Tens of thousands of northern Israelis have been displaced from their homes by those attacks — and Israel has said its war with Hezbollah is aimed at stopping those rockets so families can return home.

On Tuesday, Kassem signaled that Hezbollah would ramp up attacks further south in Israel, which it has already done by targeting Tel Aviv and Haifa. Kassem has headed the militant group since Sept. 27, when its longtime leader, Hassan Nasrallah, was assassinated in an Israeli airstrike.

Hezbollah began targeting Israel with rockets on Oct. 8, 2023, a day after the Hamas attack on Israel that left 1,200 dead and 250 as hostages in Gaza.

Israel's ensuing war against Hamas has left more than 42,000 people dead in Gaza, according to local health officials. They do not differentiate between fighters and civilians, but have said a little more than half the dead are women and children. Hezbollah has insisted it will continue to target Israel until a cease-fire in Gaza is reached.

“We cannot separate Lebanon from Palestine, or Palestine from the world,” Kassem said.

Read more: Israeli strike in Beirut kills 9 as troops battle Hezbollah in southern Lebanon

Also on Tuesday, Pentagon press secretary Maj. Gen. Pat Ryder announced the arrival of U.S. troops in Israel on Monday. The team will operate a Terminal High-Altitude Area Defense battery there to defend against ballistic missile attacks from Iran, which backs both Hezbollah and Hamas, and has launched two missile attacks on Israel.

“Over the coming days, additional U.S. military personnel and THAAD battery components will continue to arrive in Israel,” Ryder said.

Iran has warned U.S. troops would be in harm’s way if they launch another attack.

In Lebanon, Israel's bombardment and ground invasion have displaced more than 400,000 children in the past three weeks, according to Ted Chaiban, deputy executive director at UNICEF, the U.N. children's agency.