Early Sunday morning, warning sirens of incoming rockets sounded across northern Israel.
There were no immediate reports of injuries.
In a statement, the IDF said Hezbollah “launched more than 150 projectiles from Lebanon toward the Israeli border.”
Mr Hagari later said that “dozens of IAF (Israeli Air Force) jets are currently attacking targets in various parts of southern Lebanon”.
Meanwhile, Hezbollah said it had already fired more than 320 Katyusha rockets, hitting 11 Israeli military bases and camps.
Israeli Prime Minister Benjamin Netanyahu said he would convene an emergency meeting of his defense cabinet.
Mr Netanyahu’s office said the prime minister and Defense Minister Yoav Galant were “managing the situation” from the IDF’s military base in Tel Aviv.
Meanwhile, Hezbollah said in a statement that its attack on Israel was “in response to the brutal Zionist aggression, which… led to the martyrdom of Fuad Shukr”.
A senior military commander of a Shiite group was killed in an Israeli airstrike July in Beirut, the capital of Lebanon.
Israel has been exchanging fire with the Lebanon-based militant group since the war with Hamas in the Gaza Strip began last October.
Hamas is backed by Iran, as is Hezbollah.
