Sparked by the Gaza war, the conflict between Iran-backed Hezbollah and Israel has been gradually intensifying for months, raising fears of a full-scale war, which both sides have indicated they want to avoid and diplomats are working to prevent.
As the latest violence played out in areas at or near the frontier, the sound of sonic booms rattled nerves for the second successive day in Beirut and other parts of Lebanon.
Israeli jets broke the sound barrier over several areas of the country, Lebanon's National News Agency reported.
Hezbollah said it launched more than 200 rockets and a swarm of drones at 10 Israeli military sites in retaliation for Israel's killing of Hezbollah commander Mohammed Nasser in the south on Wednesday.
Nasser is one of the most senior Hezbollah commanders to be killed by Israel during the conflict.
The Israeli military said about "200 projectiles and over 20 suspicious aerial targets were identified crossing from Lebanon into Israeli territory", a number of which were intercepted by Israeli air defences and fighter jets.
Israel's ambulance service said no casualties were reported.
The Israeli military said some of the drones and interceptor shrapnel set off fires.
The Israeli air force "struck Hezbollah military structures" in the areas of Ramyeh and Houla", it said, referring to two villages in south Lebanon.
Senior Hezbollah official Hashem Safieddine, speaking at an event in Beirut commemorating Nasser, indicated his group would widen its targeting.
"The series of responses continues in succession, and this series will continue to target new sites that the enemy did not imagine would be hit," Safieddine said.
The United States has been leading diplomatic efforts to de-escalate the fighting.
Hezbollah has said it will not cease fire as long as Israel continues its offensive in the Gaza Strip.
Amos Hochstein, a senior US official at the heart of the diplomacy, discussed French and American efforts to restore calm in meetings with French officials on Wednesday, a White House official said.
Israeli Defence Minister Yoav Gallant said on Wednesday that Israeli forces were hitting Hezbollah "very hard every day" and would be ready to take any action necessary against the group, though the preference is to reach a negotiated arrangement.
Hezbollah also launched rockets at Israel on Wednesday in retaliation for Nasser's killing.
Hezbollah began firing at Israeli targets along the border with Lebanon after its Palestinian ally Hams launched an attack on Israel on October 7, declaring its support for the Palestinians.
Israeli attacks in Lebanon have killed more than 300 Hezbollah fighters and some 90 civilians, according to Reuters tallies.
Israel says fire from Lebanon has killed 18 soldiers and 10 civilians.
