A spokesman for the U.S. National Security Council, Sean Savett, said Sunday that President Joe Biden was “closely monitoring events in Israel and Lebanon,” after Hezbollah said it fired hundreds of rockets and drones at Israel to avenge Fouad Shukur's killing and Israel said it struck 40 Hezbollah targets in south Lebanon to foil the attack.

“At his direction, senior U.S. officials have been communicating continuously with their Israeli counterparts,” Savett added.

U.N. Special Coordinator for Lebanon Jeanine Hennis-Plasschaert and the U.N. Interim Force in Lebanon (UNIFIL) on Sunday called on Israel and Hezbollah to “cease fire and refrain from further escalatory action,” in light of the “worrying developments across the Blue Line since the early morning.”

Israeli Defense Minister Yoav Gallant announced a 48-hour nationwide state of emergency from 06:00 am (0300 GMT) Sunday, after the Israeli military launched what it called pre-emptive strikes in south Lebanon.

"The declaration on the state of emergency enables the IDF (Israeli military) to issue instructions to the citizens of Israel, including limiting gatherings and closing sites where it may be relevant," Gallant said, in a statement issued by his office.

Israeli Prime Minister Benjamin Netanyahu vowed Sunday "to do everything" to ensure the security of residents of northern Israel after the military launched massive air strikes against Hezbollah targets in southern Lebanon and the Lebanese group said it had avenged the killing of its military chief Fouad Shukur.

"We are determined to do everything to protect our country, return the residents of the north safely to their homes and continue to follow a simple rule: whoever hurts us, we hurt them," Netanyahu said in a statement issued by his office.

Lebanon's health ministry said three people were killed Sunday in Israeli raids in the country's south, after Israel launched strikes against Hezbollah, which announced a wide-scale attack on Israel.

An "Israeli drone strike on a car in the village of Khiam" killed one person, the health ministry said in a statement.

Hezbollah said its chief Sayyed Hassan Nasrallah will speak later Sunday after the Lebanese group announced it had launched a large-scale attack on Israel in response to Fouad Shukur's assassination, and Israeli forces struck Lebanon.

Nasrallah will speak at 6:00 pm (1500 GMT), addressing "the latest developments," a statement from the group said.

Israel launched a wave of airstrikes across southern Lebanon early Sunday in what it said was a pre-emptive strike on Hezbollah, as the group said it had launched hundreds of rockets and drones to avenge the killing of one of its top commanders last month.

The Israeli military said its fighter jets attacked "thousands" of Hezbollah rocket launchers in south Lebanon that were aimed at northern and central Israel.

A war monitor said Israeli air strikes on Syria targeting positions of the army and its Lebanese ally Hezbollah killed three Iran-backed fighters on Friday.

U.S. Ambassador Lisa A. Johnson toured Friday the Berbara Fishermen Cooperative to view the newly renovated facility, which is now a vibrant destination that drives economic opportunity for the local community.

With support from the United States Government through the United States Agency for International Development (USAID), the Berbara Fishermen Cooperative recently upgraded their infrastructure with a pre-built kiosk and restroom (accessible to People with Disabilities – PWDs); bolstered their operations with a new wastewater treatment unit and kitchen equipment; and built local fishermen's’ expertise in food safety, operations, and management, the U.S. Embassy in Beirut said.

In Lebanon's biggest public hospital, nurses are busy honing their life-saving skills as the specter of all-out war looms, 10 months into intensifying clashes between Hezbollah and Israel over the Gaza war.

"We are in a state of readying for war," nurse Basima Khashfi said as she gave emergency training to young nurses and other staff at the hospital in Beirut.