The Israeli military has announced that Hezbollah leader Hassan Nasrallah was killed in an airstrike in southern Beirut Friday and Hezbollah has reportedly launched a "rocket barrage" on multiple Israeli targets in response.
Hezbollah has yet to confirm the death of Nasrallah, who was one of the founders of the Iranian-backed force.
Iran's Supreme Leader Ali Khamenei sent a message of assurance to Hezbollah on Saturday, saying that "all regional resistance forces" are standing with the group, CNN reported.
Khamenei insisted that Israel was "too small to cause significant damage" to Hezbollah.
"It is obligatory for all Muslims to stand proudly with the people of Lebanon and Hezbollah with their resources and help it in confronting the usurping, cruel and evil regime," his statement added.
The Hezbollah strikes Saturday reportedly targeted Rosh Pina, Sa'ar and Avivim in northern Israel.
Rocket sirens were activated in Safed and the Upper Galilee, according to Israel's Home Front Command, CNN reported. Earlier, the Israel Defense Forces said a rocket was intercepted over the West Bank.
No injuries were immediately announced following the Hezbollah strikes.
Israel continued to launch strikes on Beirut over night into early Saturday, claiming to target Hezbollah weapons.
Hundreds have been killed in the recent series of Israeli bombardments, and some 100,000 people have been displaced by the attacks, according to Lebanese authorities.
Israel warned that the assaults on Lebanon are "not the end of our toolbox."
