Hezbollah leader Hassan Nasrallah was killed in an Israeli airstrike on Friday.
Israel is firing strikes into Lebanon as the conflict in the Middle East intensifies.
Israel believes it has eliminated around 30 top Hezbollah leaders over the last several weeks, including Hezbollah leader Hassan Nasrallah, who was killed in an Israeli airstrike in Beirut on Friday, U.S. and Israeli officials said.
White House National Security spokesman John Kirby said on ABC News' "This Week" that Hezbollah's command structure has been "nearly decimated" and that thousands of the terrorist group's drones and missiles have been destroyed.
"There's no question that the Hezbollah of today is not the Hezbollah that was even just a week ago," Kirby told ABC's Martha Raddatz.
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The Israel Defense Forces said it conducted an airstrike on a school in Gaza, in the northern city of Beit Lahiya, to target "terrorists who were operating inside a Hamas command and control center."
Four people were killed and 15 were wounded, according to Gaza Civil Defense.
The death toll in Gaza since Oct. 7 now stands at 41,595, according to the Gaza Ministry of Health.
Hezbollah confirmed on Sunday that Ali Karaki -- the commander of the militant group's southern front -- was among those killed alongside leader Hassan Nasrallah in an Israeli airstrike in southern Beirut on Friday.
Karaki fought for Hezbollah since 1982, Hezbollah said in a statement. Karaki was "responsible for leading the southern front with all its axes and units" in the group's cross-border fighting with Israeli forces that began on Oct. 8, the statement added.
The Israel Defense Forces reported Karaki's death on Saturday in a statement detailing the strike that killed Nasrallah.
-ABC News' Ghazi Balkiz and Victoria Beaule
Lebanon's caretaker Prime Minister Najib Mikati told reporters Sunday that some 1 million people may have been displaced amid Israel's strikes on Hezbollah.
"There are a million Lebanese people who have moved from one place to another, and this may be the largest displacement operation that has occurred," Mikati said.
Lebanon's total population as of 2022 was 5.5 million people, per World Health Organization data.
Israel's intense airstrike campaign has been especially punishing for Lebanese people living in Hezbollah heartlands, notably the south and east of the country as well the densely populated southern Beirut suburb of Dahiya.
Lebanese officials said Israeli strikes have killed at least 1,030 people in Lebanon since Sept. 16, when Israel detonated thousands of pager devices used by Hezbollah members. Israel detonated Hezbollah walkie-talkies the following day and then intensified its nationwide airstrike campaign.
Among those confirmed dead since Sept. 16 are 56 women and 87 children. Some 6,352 people have been wounded.
"The security forces will intensify their measures to protect shelters and the displaced and ensure peace and security in the regions and on the roads," Mikati said Sunday.
"We are following up on the issue of public health in shelters to avoid the spread of any diseases," the caretaker prime minister added.
"We are following up on the affairs of the displaced in full through the relevant ministries, and the state is doing everything necessary within its capabilities to secure the displaced."
"Thanks to all those who have embraced the displaced."
Lebanon's government, Mikati added, is "committed to a diplomatic solution to reach a ceasefire."
-ABC News' Ghazi Balkiz and Victoria Beaule
