An Israeli airstrike hit an apartment building in northern Lebanon on Monday, killing at least 21 people, according to the Lebanese Red Cross.

The Israeli military did not immediately comment and the target was not clear. The strike hit a small apartment building in the village of Aito, which is part of the country's Christian heartland in the north and far from the Hezbollah militant group's main areas of influence in the south and east.

Rescue workers in Aito searched through the rubble of the building as ambulances stood by to receive the bodies of victims. Nearby buildings and cars were damaged in the strike.

UN peacekeepers in southern Lebanon are in the crosshairs of Israel’s war on Hezbollah

The strike came a day after a Hezbollah drone attack on an army base in northern Israel killed four soldiers — all of them 19 years old — and severely wounded seven others in the deadliest strike by the militant group since Israel launched its ground invasion of Lebanon nearly two weeks ago.

On Monday, Prime Minister Benjamin Netanyahu visited the army base and soldiers wounded in the attack, vowing “we will continue to strike Hezbollah without compassion in every part of Lebanon, including in Beirut.”

Sixty-one people were wounded in Sunday's attack. Hezbollah has fired thousands of rockets, missiles and drones into Israel over the past year, killing more than 60 people, although Israel says most have been intercepted by its air defense systems or hit open areas.

In Lebanon, some 2,300 people have been killed by Israeli strikes since last October, according to the country's Health Ministry. More than three-quarters of the deaths occurred in the past month.

Hezbollah, an ally of Hamas, has vowed to keep up its attacks on Israel until there is a cease-fire in Gaza. Israel has said its campaign against Hezbollah is aimed at stopping those attacks so displaced Israelis can feel safe returning to their homes near the Lebanese border.

A strike and an inferno in a Gaza hospital courtyard
Earlier on Monday, an Israeli airstrike on a hospital courtyard in the Gaza Strip killed at least four people and triggered a fire that swept through a tent camp for people displaced by the war, leaving more than two dozen with severe burns.

The Israeli military said the strike in Gaza targeted militants hiding among civilians, without providing evidence. In recent months it has repeatedly struck crowded shelters and tent camps, alleging that Hamas fighters were using them as staging grounds for attacks.

Al-Aqsa Martyrs Hospital in the central city of Deir al-Balah was already struggling to treat a large number of wounded from an earlier strike on a school-turned-shelter that killed at least 20 people when the early morning airstrike hit and fire engulfed many of the tents.

Several secondary explosions could be heard after the initial strike, but it was not immediately clear if they were caused by weapons or fuel tanks.

Associated Press footage showed children among the wounded. A man sobbed as he carried a toddler with a bandaged head in his arms. Another small child with a bandaged leg was given a blood transfusion on the floor of the packed hospital.

Hospital records showed that four people were killed and 40 wounded. Twenty-five people were transferred to Nasser Hospital in southern Gaza after suffering severe burns, according to Al-Aqsa Martyrs Hospital.

The Biden administration called the strike on Al Aqsa Martyr’s Hospital “deeply disturbing” and said it has expressed concerns about it to the Israeli government.

“Israel has a responsibility to do more to avoid civilian casualties — and what happened here is horrifying, even if Hamas was operating near the hospital in an attempt to use civilians as human shields,” the White House National Security Council said in a statement.

The war began when Hamas attacked southern Israel on Oct. 7, 2023, killing some 1,200 people, mostly civilians, while Palestinian militants abducted around 250 hostages. Around 100 are still being held inside Gaza, a third of whom are believed to be dead.

Israel's retaliatory offensive has killed over 42,000 Palestinians, according to Gaza's Health Ministry, which does not say how many were fighters but says women and children make up more than half the fatalities. Around 90% of Gaza's population of 2.3 million people have been displaced by the war, often multiple times, and large areas of the coastal territory have been completely destroyed.

Israeli rights groups warn of forced transfer in northern Gaza
Israel has ordered the entire remaining population of the northern third of Gaza, estimated at around 400,000 people, to evacuate to the south and has not allowed any food to enter the north since the start of the month. Hundreds of thousands of people from the north heeded Israeli evacuation orders at the start of the war and have not been allowed to return.

That has raised fears among Palestinians that Israel intends to implement a plan devised by former generals in which it would order all civilians out of northern Gaza and label anyone remaining there a combatant — a surrender-or-starve strategy that rights groups say would violate international law.

The plan has been presented to the Israeli government, but it's unclear whether it has been adopted. The military says it has not received such orders.

Israeli rights groups on Monday called on the international community to prevent Israel from carrying out the plan, saying there are “alarming signs” that Israel is beginning to implement it.

The statement, signed by B'Tselem, Gisha, Yesh Din and Physicians for Human Rights-Israel, warned that states “have an obligation to prevent the crimes of starvation and forcible transfer."

On Monday, the Israeli military said it allowed 30 trucks carrying flour and food into north Gaza. COGAT, the Israeli military body that oversees aid distribution in Gaza, said the trucks entered northern Gaza through the Erez crossing.