A powerful airstrike killed 11 people in central Beirut on Saturday, the health ministry said, shaking the capital as Israel pressed its offensive against the Iran-backed Hezbollah group.

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.

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.