An uprooted tree lays on a house as Hurricane Ida hits Morgan City, Louisiana, the United States, on Aug. 29, 2021.(Photo: Xinhua)

 

Trees along a street are blown by strong wind before Hurricane Ida's landfall in New Orleans, Louisiana, the United States, on Aug. 29, 2021.(Photo: Xinhua)

 

Sandbags are piled up at the door of a supermarket to prevent possible flooding caused by Hurricane Ida in New Orleans, Louisiana, the United States, on Aug. 29, 2021.(Photo: Xinhua)

 
With stranded people waiting for rescue on damaged roofs, flooded roads blocked by downed trees and power lines, and over one million people without power through Monday morning, Hurricane Ida has wreaked widespread havoc since its landfall in southern U.S. state of Louisiana on Sunday.

The hurricane was downgraded to a tropical storm over southwestern Mississippi on early Monday morning, about 16 hours after striking the state as a Category 4 hurricane, the U.S. National Hurricane Center (NHC) said.

However, it continues to leave a path of damage. There are four flash flood emergencies in place for portions of southeastern Louisiana through late Monday morning, according to a CNN report.

A tornado watch has been issued for portions of Mississippi, Alabama and Florida that is in effect through Monday afternoon.

PowerOutage.US reported that the hurricane had triggered a massive blackout across the region, leaving at least 1 million customers in Louisiana and 80,000 more in Mississippi without power as of early Monday morning.

Hundreds of boats, high-water vehicles and helicopters headed out on Monday across southern Louisiana in search of residents trapped on rooftops as floods overwhelmed their neighborhoods.

In Slidell, Louisiana, Mayor Greg Cromer said there is water in "every neighborhood in town" and local officials had to deploy boats to rescue 15 residents off their home roofs early Monday morning.

"In about a three hour period, we had probably five to six foot rise in the bayou and the lake estuary system that pushed water into a number of people's homes on the south side of our community," Cromer said.

At least one person was confirmed dead due to a fallen tree on his home in Prairieville, Louisiana, Ascension Parish Sheriff's Office said on Sunday night. The 60-year-old man was pronounced dead at the scene.

Louisiana Governor John Bel Edwards told MSNBC on Monday that he "fully expects the death count will go up considerably throughout the day" as search and rescue efforts get underway in the wake of Ida.

Almost all of southeast Louisiana is without power and that all eight major transmission lines that feed electricity into the greater New Orleans area have failed, said the governor.

Road and debris cleanup alone "is going to be a fairly long ordeal," he said.

Some New Orleans officials said it could be "weeks" before the power supply is restored, according to local media reports.

"The full extent of damage is yet to be seen," Louisiana state police said in a Facebook post on Monday, noting that search and rescue workers are still not able to access certain impacted areas.

U.S. President Joe Biden declared a major disaster in Louisiana and ordered federal aid to supplement recovery efforts in the Ida-hit areas, the White House said on Sunday.

"Assistance can include grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses, and other programs to help individuals and business owners recover from the effects of the disaster," the White House said.

Ida landed on the 16th anniversary of Hurricane Katrina's strike, tying with 2020's Hurricane Laura and the Last Island Hurricane of 1856 as the strongest ever to hit Louisiana.