Tropical Depression Helene brought life-threatening flooding on Friday to wide sections of the U.S. Southeast, where at least 43 people have been killed by a storm that swamped neighborhoods, triggered mudslides, threatened dams and left more than 3.5 million homes and businesses without power.

Before moving north through Georgia and into Tennessee and the Carolinas, Helene hit Florida's Big Bend region as a powerful Category 4 hurricane on Thursday night, packing 140 mph (225 kph) winds. It left behind a chaotic landscape of overturned boats in harbors, felled trees, submerged cars and flooded streets.

By early Friday afternoon, the storm had been downgraded to a tropical depression with maximum sustained winds of 35 mph (55 kph), the National Hurricane Center said.