Dozens of people have been killed by Israeli strikes in Lebanon, including 20 who died after a strike flattened a multi-story residential building in central Beirut overnight, according to Lebanese officials.

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.

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.