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 strikes were the fourth on Beirut in less than a week. The escalation comes after a U.S. envoy traveled to the region this week in an attempt to broker a cease-fire between Israel and Hezbollah.

Israeli airstrikes have killed at least 11 people and injured dozens in central Beirut, as diplomats scramble to broker a cease-fire.