Hezbollah pounded northern Israel with 140 rockets Friday, a day after the militant group's leader, Hassan Nasrallah, vowed to retaliate against Israel for a mass bombing attack, the Israeli military and the militant group said.

Israel's military said the rockets came in three waves Friday afternoon, targeting sites along the ravaged border with Lebanon.

The Israeli military said it had carried out a "targeted strike" in Beirut. It offered no further immediate details, but explosions could be heard coming from the city's southern suburbs.

Beirut-based Al-Mayadeen TV reported that a drone fired several missiles on the heavily-populated area known as Dahiyeh.

Hezbollah said its attacks had targeted several sites along the border with Katyusha rockets, including multiple air defence bases as well as the headquarters of an Israeli armoured brigade they said they'd struck for the first time.

The Israeli military said 120 missiles were launched at areas of the Golan Heights, Safed and the Upper Galilee, some of which were intercepted. Fire crews were working to extinguish blazes caused by pieces of debris that fell to the ground in several areas, the military said.

The military did not say whether any missiles had hit targets or caused any casualties.

Another 20 missiles were shot at the areas of Meron and Netua, and most fell in open areas, the military said, adding no injuries were reported.

WATCH l Hezbollah's Hassan Nasrallah reacts to attacks he blames on Israel:

Pager attacks crossed 'red lines,' Hezbollah chief says

Hezbollah leader Hassan Nasrallah accused Israel on Thursday of targeting thousands of pagers in a wave of attacks that hit Lebanon this week. Israel has neither confirmed nor denied its involvement in the explosions.

Not related to device attacks, Hezbollah says

Hezbollah said the rockets were in retaliation for Israeli strikes on villages and homes in southern Lebanon, and not the two days of attacks widely blamed on Israel that set off explosives in thousands of pagers and walkie-talkies.

Hezbollah and Israel have exchanged near-daily fire since Oct. 8, a day after the Israel-Hamas war's opening salvo, but Friday's rocket barrages were heavier than normal.

WATCH l Israel is party to prohibitions on type of weapons indiscriminate attacks: analyst

Does the use of exploding pagers in Lebanon violate laws? | Canada Tonight

Some experts indicate that the explosions of wireless communication devices in Lebanon, part of a series of attacks widely believed to have been carried out by Israel, likely breach the laws of war. Brian Finucane, senior adviser for the U.S. program at the International Crisis Group, discusses this on Canada Tonight.

Nasrallah on Thursday vowed to keep up daily strikes on Israel despite this week's deadly sabotage of its members' communication devices, which he described as a "severe blow."

At least 20 were killed in the attacks and thousands were wounded when pagers, walkie-talkies and other devices exploded in Lebanon on Tuesday and Wednesday.

The sophisticated attacks have heightened fears that the cross-border exchanges of fire will escalate into all-out war. Israel has neither confirmed nor denied involvement in the attacks.

In recent days, Israel has moved a powerful fighting force up to the northern border, officials have escalated their rhetoric and the country's security cabinet has designated the return of tens of thousands of displaced residents to their homes in northern Israel an official war goal.

Israeli airstrike in Gaza kills at least 15

Meanwhile, fighting in Gaza has slowed, but casualties continue to rise.

Overnight, Palestinian authorities said 15 people were killed in multiple Israeli attacks in the Gaza Strip.

Those included six people, including an unknown number of children, in an airstrike early Friday morning in Gaza City that hit a family home, Gaza's Civil Defence said. Another person was killed in Gaza City when a strike hit a group of people on a street.

Israel maintains it only targets militants and accuses Hamas and other armed groups of endangering civilians by operating in residential areas. The military, which rarely comments on individual strikes, had no immediate comment.

Gaza's Health Ministry says more than 41,000 Palestinians have been killed and more than 95,000 wounded in the territory since the war started. The ministry does not differentiate between fighters and civilians in its count, but says a little over half of those killed were women and children.

The war has caused vast destruction and displaced about 90 per cent of Gaza's population of 2.3 million.

LISTEN l 2 longtime Middle East reporters on the turn in Israeli-Hezbollah hostilities:

The war was started when Hamas led attacks in southern Israel on Oct. 7 which killed 1,200 people, including several Canadians, according to Israeli government tallies.

More than 250 hostages were taken then, Israel said. Just over 100 hostages remain unaccounted for after repatriations, but the Israeli government believes about one-third of that total represents people who are no longer alive.