A powerful Israeli air strike flattened a residential building in central Beirut early Saturday, killing at least 11 people and wounding 63 others, according to witnesses and the Health Ministry's initial count.

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.

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.