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.

The strikes, which destroyed an eight-story building and left a crater in the ground, were the fourth in Beirut in less than a week.

The escalation comes after a U.S. envoy traveled to the region to pursue a deal to end months of fighting between Israel and Hezbollah.