An airstrike has leveled an apartment building and killed three Palestinian militants in central Beirut, as Israel appeared to send a clear message that no part of Lebanon is out of bounds.

Israel bombed the center of Beirut for the first time in almost a year of hostilities with Lebanon’s Hezbollah, as the military steps up air assaults following the killing of the Iran-backed group’s chief last week.

Hezbollah tried to project continuity of leadership and mission Saturday, saying it would continue “confronting the enemy.”