Louisiana and Mississippi took stock Tuesday of the disaster inflicted by powerful HurricaneIda, 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 under a curfew Tuesday evening, 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.
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.
Mayor LaToya Cantrell said on Twitter she had signed an executive order mandating an overnight curfew in New Orleans, most of which was still entirely without power after the storm.
Satellite pictures show damage
Combination of satellite image houses in Lafitte and Barataria, Louisiana shows storm damage in Lafitte and Barataria, Louisiana in the aftermath of Hurricane Ida.
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.
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.
Ida knocked out power for more than a million properties across Louisiana, according to outage tracker PowerOutage.us, most of which still out Tuesday evening, leaving residents without air conditioning in late summer.
Satellite image shows building in LaPlace, Louisiana in the aftermath of Hurricane Ida.
Entergy had initially said it could take days to even assess the full extent of the damage.
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.
Louisiana, Mississippi get access to federal aid
President Joe Biden had 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.
Ida -- now a tropical depression -- was travelling northeast, threatening the Tennessee and Ohio Valleys. It was expected in the mid-Atlantic on Wednesday, according to the National Hurricane Center.
New Orleans defenses hold
New Orleans, still scarred by the devastation wrought 16 years ago by Hurricane Katrina, held its breath as Ida bore down this week. But this time, the city's flood defenses prevailed.
In the wake of the 2005 storm that killed over 1,800 people and submerged whole swaths of New Orleans, the US government spent $14.5 billion on levees, pumps and other protections for the city and nearby suburbs.
"Ida came onshore with everything that was advertised: the surge, the rain, the wind," Louisiana governor John Bel Edwards told a briefing Monday.
"The good news, first, is all of our levee systems... performed magnificently," he added.
New Orleans surrounded by water
Located at the mouth of the Mississippi River and in an area below sea level, New Orleans is surrounded by water, with the giant, briny Lake Pontchartrain to the north and the Gulf of Mexico to the south.
Given the city's geography, as well as Ida's lashing 150-mile (240-kilometer) per hour winds, storm surge and heavy rains, the danger to New Orleans' 390,000 people was very real.
But no levee in the city was breached or overtopped. Edwards said that feat could be traced to 16 years ago.
Under the battering from Katrina's flood waters, more than 50 levees broke and 80 percent of the city was submerged, with water reaching 20 feet (six meters) in places. Billions of dollars in damage was done.
Louisiana passed initial test in 2012
After Katrina, a 130-mile ring of barriers was built to withstand a storm surge of up to 30 feet.
Huge gates now allow water to drain away to Lake Ponchartrain or the Gulf of Mexico, while preventing water from entering the city, said Poche.
The protection system also includes more than 70 pumps, which drain water in the event of street flooding.
"After Katrina... it was important that the system was structurally superior -- higher levees, higher wall and resilient," he added.
The levees in Louisiana's largest city had already passed an initial test during Hurricane Isaac in August 2012, which caused little damage.
In the town of Jean Lafitte, just south of New Orleans, mayor Tim Kerner said the rapidly rising waters had overtopped the 7.5-foot-high (2.3-meter) levees.
"Total devastation, catastrophic, our town levees have been overtopped," Kerner told ABC-affiliate WGNO.
"We have anywhere between 75 to 200 people stranded in Barataria," after a barge took out the swing bridge to the island.
Cynthia Lee Sheng, president of Jefferson Parish covering part of the Greater New Orleans area, said people were sheltering in their attics.
Several residents of La Place, just upstream from New Orleans, posted appeals for help on social media, saying they were trapped by rising flood waters.