Lebanon’s Hezbollah group has confirmed that its leader and one of its founders, Hassan Nasrallah, was killed in an Israeli airstrike.

A statement on Saturday said Nasrallah “has joined his fellow martyrs.” The statement says Hezbollah vows to “continue the holy war against the enemy and in support of Palestine.” Nasrallah led the militant group for more than three decades.

Earlier, Israel had said that it killed Hezbollah leader Hassan Nasrallah, dealing its most significant blow to the Lebanese militant group after months of fighting.

Nasrallah is by far the most powerful target to be killed by Israel in weeks of intensified fighting with Hezbollah. Ali Karki, the Commander of Hezbollah’s Southern Front, and additional Hezbollah commanders, were also killed in the attack, the Israeli military said. The military said it carried out a precise airstrike on Friday while Hezbollah leadership met at their headquarters in Dahiyeh, south of Beirut.

Israel’s Chief of Staff, Lt Gen Herzi Halevi, said Saturday that the elimination of Nasrallah was “not the end of our toolbox,” indicating that more strikes were planned. He said that the strike targeting Hezbollah leadership was the result of a long period of preparation.

The Lebanese Health Ministry said six people were killed and 91 injured in the strikes Friday, which leveled six apartment buildings.

The Israeli military said it was mobilising additional reserve soldiers as tensions escalate with Lebanon, activating three battalions of reserve soldiers to serve across the country. The call comes after it sent two brigades to northern Israel earlier in the week to train for a possible ground invasion.

On Saturday morning, the Israeli military carried out several strikes in southern Beirut and eastern Lebanon’s Bekaa Valley. Hezbollah launched dozens of projectiles across northern and central Israel and the Israel-occupied West Bank.

In Beirut’s southern suburbs, smoke rose and the streets were empty after the area was pummeled overnight by heavy Israeli airstrikes. Shelters set up in the city centre for displaced people were overflowing. Many families slept in public squares and beaches or in their cars. On the roads leading to the mountains above the capital, hundreds of people could be seen making an exodus on foot, holding infants and whatever belongings they could carry.

At least 720 people have been killed in Lebanon over the past week from Israeli airstrikes, according to the Health Ministry.