Hurricane Ida has claimed at least one life in the US as it pushes its way inland bringing torrential rain and shrieking winds.
The victim was hit by a falling tree outside Baton Rouge, Louisiana.
Scores of residents along the coast of the southern state were left pleading to be rescued from floodwaters on Monday as the extreme weather moved inland towards Mississippi.
Violent wind pushed so much water into the mouth of the Mississippi that it reversed the flow of the mighty river and blacked out New Orleans.
The city lost power at sunset on Sunday as the hurricane blew ashore on the 16th anniversary of Katrina, leading to an uneasy night of pouring rain and howling wind.
One of the most powerful hurricanes ever to hit the US mainland, it weakened into a tropical storm overnight with the full extent of its fury still coming into focus at daybreak.
People began walking around neighbourhoods with flashlights as the weather died down while avoiding fallen street lights, roof tiles and branches.
Chris Atkins was in his New Orleans home when he heard a “kaboom” and all the sheetrock in the living room fell into the house.
A short time later, the whole side of the living room fell onto his neighbour’s driveway.
“I had a miserable night. Lucky the whole thing didn’t fall inward. It would have killed us,” he said.
Around 17 inches of rain fell in 20 hours in an area just west of the city, according to forecasters.
Hundreds of homes were threatened by the flooding which caused a surge in the maze of rivers and bayous south of New Orleans.
Desperate residents posted their addresses and directed search and rescue teams to their attics or rooftops.
Hundreds of rescue boats were launched into the floodwaters in the morning.
The Louisiana National Guard said it activated 4,900 Guard personnel and lined up 195 high-water vehicles, 73 rescue boats and 34 helicopters.
Some 500 people said they were going to stay in areas which were flooded in Jefferson Parish, parish council member Deano Bonano told WWL-TV.
“I know people have family members in here they are trying to check on. They can’t get to them. The water is too high. We’re going to do our best efforts to get them out,” Bonano said.
More than a million customers in Louisiana and Mississippi were without power, according to PowerOutage.
Entergy said all eight major transmission lines into New Orleans were down and the only power was coming from generators, the city’s emergency office tweeted.
New Orleans’ levees underwent major improvements after Katrina which in 2015 breached the city’s flood defenses, causing catastrophic flooding and 1,500 deaths.
Ida posed its biggest test since that disaster.
No major flooding was reported inside the flood control system that protect New Orleans.
Entire neighborhoods in Mississippi were surrounded by floodwaters and many roads were impassable.
Ida was expected to pick up speed Monday night before dumping rain on the Tennessee and Ohio River valleys Tuesday, the Appalachian mountain region Wednesday and the nation’s capital on Thursday.
Forecasters said flash flooding and mudslides are possible along Ida‘s path before it blows out to sea over New England on Friday.