New Orleans (AFP) -
Louisiana and Mississippi took stock Tuesday of the disaster inflicted by powerful Hurricane Ida as receding floodwaters began to reveal the full extent of the damage along the US Gulf Coast and the death toll rose to four.
New Orleans was still mostly without power nearly two days after Ida slammed into the Louisiana coast as a Category 4 storm, exactly 16 years after devastating Hurricane Katrina -- which killed more than 1,800 people -- made landfall.
'Full damage assessment could take several days, as many areas are currently inaccessible,' power provider Entergy said Tuesday.
Four deaths have been confirmed as crews began fanning out in boats and off-road vehicles to search communities cut off by the giant storm. A man was also missing after apparently being killed by an alligator.
Images of people being plucked from flooded cars and pictures of destroyed homes surfaced on social media, while the damage in New Orleans itself remained limited.
New Orleans Airport said all incoming and outgoing flights scheduled for Tuesday were canceled, while airlines had scrapped nearly 200 flights on Wednesday.
Ida -- which has now been downgraded to a tropical depression -- knocked out power for more than a million properties across Louisiana, according to outage tracker PowerOutage.us.
One person was killed by a falling tree in Prairieville, while a second victim died trying to drive through floodwaters some 60 miles (95 kilometers) southeast in New Orleans, officials reported.
In Mississippi, which has been buffeted by torrential rain, a road collapse left two people dead and 10 more injured, including three in critical condition, the state's highway patrol said.
The death toll is expected to rise further, Louisiana Deputy Governor Billy Nungesser warned Tuesday, especially in coastal areas directly hit by Ida where search and rescue operations are ongoing.
Meanwhile in St. Tammany Parish, police said a 71-year-old man was attacked and 'apparently killed by an alligator while walking in flood waters following Hurricane Ida.'
- Ida heads northeast -
President Joe Biden declared a major disaster for Louisiana and Mississippi, which gives the states access to federal aid.
Louisiana Governor John Bel Edwards said his state had deployed more than 1,600 personnel for search and rescue operations, while the Pentagon said over 5,200 personnel from the military, federal emergency management and National Guard had been activated across several southern states.
As Ida travels northeast, considerable heavy rain and flooding is expected to threaten the Tennessee and Ohio Valleys and move onward into the mid-Atlantic through Wednesday, according to the National Hurricane Center.
As of 0900 GMT Tuesday, Ida was about 185 miles southwest of country music hub Nashville, Tennessee, with maximum sustained winds of 30 miles per hour.
Scientists have warned of a rise in cyclone activity as the ocean surface warms due to climate change, posing an increasing threat to the world's coastal communities.