Israeli airstrikes Saturday in central Beirut killed at least 20 people, officials said, as the once-rare attacks on the heart of Lebanon's capital continued without warning while diplomats scrambled to broker a cease-fire.

At least 15 people have been killed and several others injured after an Israeli strike flattened a multi-story residential building in central Beirut overnight, Lebanese officials said.

Saturday’s attack completely demolished a multi-story building in a densely-populated neighborhood. Israel did not say who the strike’s target was.