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.

Israel was targeting a senior Hezbollah commander, but failed to kill him, one Israeli official said. Hezbollah officials said none of the group’s leaders were at the attack site.