An Israeli strike on a Beirut apartment block killed four people on Monday, a Lebanese security source said, the first such raid on the heart of the city since the outbreak of the war in Gaza last year.

Israel has turned its focus from Gaza to Lebanon in recent days, carrying out strikes on Hezbollah targets that killed the Iran-backed group's leader Sayyed Hassan Nasrallah on Friday.

The Israeli military said on Sunday its air force had struck "dozens of Hezbollah terror targets" after carrying out "hundreds" of strikes on Friday and Saturday.

Lebanon's National News Agency reported a string of raids in and around the city of Baalbek in the east.

The Israeli strike that killed Hezbollah's leader Sayyed Hassan Nasrallah was a "measure of justice" for victims of a four-decade "reign of terror," U.S. President Joe Biden said.

The comments came after Hezbollah confirmed that Nasrallah, one of the group's founders, was killed in an Israeli airstrike in Beirut's southern suburbs the previous day.

Israeli Prime Minister Benjamin Netanyahu said that Israel had "settled the score" with the killing of Hezbollah chief Sayyed Hassan Nasrallah in an air strike in Dahiyeh.

"We settled the score with the one responsible for the murder of countless Israelis and many citizens of other countries, including hundreds of Americans and dozens of French," he said in his first statement since Nasrallah's death on Friday.

Pope Francis called for an immediate ceasefire in "martyred" Lebanon and the wider Middle East as he ended a three-day visit to Belgium.

"I call on all parties to immediately cease fire in Lebanon, Gaza, the rest of Palestine and Israel," the Argentinian pontiff, 87, told an open-air mass in Brussels, as Israel continued to target Hezbollah in Lebanon.

Caretaker Prime Minister Najib Mikati announced Sunday that Lebanon is "committed to Resolution 1701" and that the army is "ready to implement it."

"We call for a ceasefire on all fronts," he said.

The Israeli military says it has killed another high-ranking Hezbollah official in an airstrike.

The military said Sunday that it killed Sheikh Nabil Qaouq, the former deputy head of Hezbollah's Executive Council, in an airstrike the day before. The Israeli army said Qaouq is a member of Hezbollah's central council and the head of the group's preventive security unit.

Lebanon’s state news agency says an Israeli airstrike early Sunday on a village in northeast Lebanon destroyed a home, killing 11 people.

Six of the bodies were recovered from under the rubble as the search continued for the remaining five in the village of al-Ain, reported National News Agency.

In its first statement since the recent escalation with Israel and following the killing of Hezbollah leader Sayyed Hassan Nasrallah, Lebanon's army called for calm among the Lebanese "at this dangerous and delicate stage."

Government officials fear that the country’s deep political divisions at a time of war could rekindle sectarian strife and violence in the small country.

Hundreds of thousands of people in Lebanon have been displaced from the ongoing conflict between Hezbollah and Israel, a Lebanese cabinet minister spearheading the country’s emergency response said.

Environment Minister Nasser Yassin said the government estimates that about 250,000 people have left their homes and taken refuge in government-run shelters and informal ones. However, he told the Associated Press the total number is about “four times as many directly affected and/or displaced outside the shelters.”