Lebanon’s Hezbollah group confirmed on Saturday that its leader and one of its founders, Hassan Nasrallah, was killed in an Israeli airstrike in Beirut the previous day.

A statement said Nasrallah “has joined his fellow martyrs.” Hezbollah vowed to “continue the holy war against the enemy and in support of Palestine.”

Nasrallah, who led Hezbollah for more than three decades, is by far the most powerful target to be killed by Israel in weeks of intensified fighting with Hezbollah. The Israeli military said it carried out a precise airstrike on Friday while Hezbollah leadership were meeting at their headquarters in Dahiyeh, south of Beirut.

The Lebanese Health Ministry said six people were killed and 91 injured in the strikes, which leveled six apartment buildings. Ali Karki, the commander of Hezbollah’s Southern Front and other commanders were also killed, the Israeli military said.

Lt. Col. Nadav Shoshani, an army spokesperson, said the airstrike was based on years of tracking Nasrallah along with “real time information” that made it viable. He declined to say what munitions were used in the strike or provide an estimate on civilian deaths, only saying that Israel takes measures to avoid civilians whenever possible and clears strikes ahead of time with intelligence and legal experts.

The Palestinian militant group Hamas in a statement issued condolences to its ally, Hezbollah. Nasrallah frequently described launching rockets against northern Israel as a “support front” for Hamas and Palestinians in Gaza.

“History has proven that the resistance … whenever its leaders die as martyrs, will be succeeded on the same path by a generation of leaders who are more valiant, stronger and more determined to continue the confrontation,” the Hamas statement said.

It added that “assassinations will only increase the resistance in Lebanon and Palestine in determination and resolve.”

Immediately after the official confirmation from Hezbollah, people starting firing in the air in Beirut and other areas of the country, to mourn Nasrallah’s death. Some were protesting that he was killed because of his support for the war in Gaza. “Wish it was our kids, not you, Sayyid!” said one woman, using an honorific title for Nasrallah, as she clutched her baby in the western city of Baabda.

Israel vows to keep up attacks on Hezbollah

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.