Others wounded in attacks on Lebanon towns of Souaneh and Aadchit while a woman was killed in Israel.
At least 11 people were wounded in the raids on the towns of Souaneh and Aadchit. One woman and her two children were killed in Souaneh while a Hezbollah fighter, named by the group as Hassan Ali Najm, was killed in Aadchit.
Wednesday’s attacks targeted several towns in southern Lebanon, including areas in Nabatieh governorate.
The strikes occurred deep inside Lebanese territory, raising fears of a new escalation between Israel and the Lebanese armed group Hezbollah after months of cross-border fire.
The UN secretary-general’s spokesman Stephane Dujarric called for a halt to increased violence.
“The recent escalation is dangerous indeed and should stop,” he said.
Peacekeepers from the UN mission in Lebanon had noticed “a concerning shift in the exchanges of fire between the Israeli armed forces and armed groups in Lebanon”, he said.
US State Department spokesman Matthew Miller called for diplomacy.
“We continue to believe that there is a diplomatic path forward and we will continue to push forward to try to resolve this issue diplomatically,” he said.
The Israeli army said Wednesday that it had launched an “extensive wave” of air strikes in Lebanon.
The attacks came after a barrage of rockets from southern Lebanon hit a military base in Safed in northern Israel, killing an Israeli solder named by the army as Sergeant Omer Sarah Benjo.
“It is being described as the biggest escalation in the ongoing confrontations between the Israeli army and the Lebanese armed group Hezbollah,” Al Jazeera’s Zeina Khodr said, reporting from Beirut. She added, however, that the escalation was still “controlled” and both sides were “sending messages” to the other party with their attacks.
While the “battleground” has been along the 120km (75-mile) border, about 4km to 5km (2.5 to 3 miles) deep on both sides, Israel “struck deeper” this time, she said.
In Israel, a rocket fired from Lebanon killed an Israeli woman, a government spokesperson said. The barrage hit a military base and wounded several other people on Wednesday, the spokesperson said.
Military and political analyst Elijah Maginer said Israel has targeted villages that are considered “very sensitive”, such as those in Nabatieh.
It is “attacking villages that have not been hit before”, Maginer told Al Jazeera.
“So it is an escalation, and I think Hezbollah will respond by the same intensity of the bombardment but without enlarging too much the war,” he said.
This means Hezbollah would likely respect “more or less the limit of the engagement” and not opt for an all-out war, which is also not in the interests of the Israelis, Maginer added.
Hezbollah chief Hassan Nasrallah said on Tuesday that his armed group’s cross-border shelling into Israel would end only when Israel’s “aggression” on the Gaza Strip stops.
The group has been trading fire with the Israeli military across Lebanon’s southern border in support of its Palestinian ally Hamas, which launched a cross-border assault from the Gaza Strip into Israel on October 7, which was followed by heavy Israeli bombardment of Gaza from the land, air and sea.
There are growing fears of another full-blown conflict between Israel and Hezbollah with tens of thousands displaced on both sides of the border and regional tensions soaring.
Cross-border attacks have killed at least 200 people in Lebanon, including more than 170 Hezbollah fighters, as well as 10 Israeli soldiers and five Israeli civilians.