Two people were killed and 10 injured when a deep crevasse opened up on a Mississippi highway in the wake of heavy rains unleashed by Hurricane Ida.
The powerful storm has left parts of Louisiana and neighbouring US states without power, officials said on Tuesday.
Three people among those injured were in critical condition, according to the Mississippi Highway Patrol.
The collapse affected a portion of Highway 26 in George County, about 80 km (50 miles) northeast of Biloxi.
Ida, one of the most powerful hurricanes ever to hit the US Gulf Coast, had weakened to a tropical depression by late Monday as it churned over Mississippi, where the system brought heavy rains overnight.
The storm, which deluged Louisiana with rain and killed at least two people in the state, caused widespread power outages across Louisiana, Mississippi and Alabama, and prompted rescue operations in flooded communities around New Orleans.
On Tuesday, officials warned residents about the hidden dangers of floodwaters that might bring wildlife closer to neighbourhoods.
Sheriff's deputies in St. Tammany Parish were investigating the disappearance of a 71-year-old man after an apparent alligator attack in the floodwaters brought on by the storm.
The man’s wife told authorities that she saw a large alligator attack her husband in the tiny Avery Estates community about 55 km (35 miles) northeast of New Orleans on Monday. She stopped the attack and pulled her husband out of the water.
Seeing that his injuries were severe, she took a small boat to get help, and came back to find her husband gone, the sheriff’s office said in a statement.
By early Tuesday, about 1.3 million customers remained without power, most of them in Louisiana, according to PowerOutage, which gathers data from US utility companies.
Entergy Corp, a major power supplier, said it could take weeks before electricity is restored in the hardest-hit areas.
Damage to eight high-voltage lines shut off electricity in New Orleans and nearby parishes, and parts of a transmission tower toppled into the Mississippi River on Sunday night.
The outages were also straining the major waste disposal systems in the city. As of Monday, 80 of the 84 sewer pumping stations had lost power, raising the risk of backups.
Ida made landfall on Sunday as a Category 4 hurricane, 16 years to the day after Hurricane Katrina, evoking memories of a disaster that killed more than 1,800 people in 2005 and devastated New Orleans.
But a $14.5 billion system of levees, flood gates and pumps designed in the wake of Katrina's devastation largely worked as designed during Ida, officials said, sparing New Orleans from the catastrophic flooding that devastated the area 16 years ago.
The state's healthcare systems also appeared to have largely escaped catastrophic damage at a time when Louisiana is reeling from a resurgence of COVID-19 infections that has strained hospitals.