Ida, one of the most powerful hurricanes ever to hit the US Gulf Coast, has knocked out power to more than one million homes in Louisiana and prompted rescue operations in flooded communities around New Orleans as the weakening storm churns northward.
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 1800 people in 2005 and devastated New Orleans.
By late Monday afternoon, after dumping a deluge of rain in Louisiana and killing at least two people, Ida was downgraded to a tropical depression as its eye crawled through neighbouring Mississippi.
Louisiana Governor John Bel Edwards said more fatalities were expected in his state.
"We didn't have another Katrina and that is something that we should be grateful for. However, the impact is absolutely significant," New Orleans Mayor LaToya Cantrell told a news conference.
President Joe Biden declared a major disaster in the state, and the Federal Emergency Management Administration (FEMA) sent 3600 of its personnel and 3.4 million meals to the storm-devastated area.
The National Guard said it has dispatched thousands of personnel as well as vehicles that can navigate flooded roads, boats and 34 helicopters to rescue people stranded by flooding.
Local officials and "Cajun Navy" disaster relief volunteers sped to the small city of Houma, where volunteers searched for people who were reported trapped by floodwaters.
Coast Guard aerial video showed widespread flooding on the island and significant roof damage to many homes.
Widespread power outages reached as far north as over 320 kilometres from where the hurricane made landfall. Many water systems in Louisiana were also out.
One transmission tower collapsed into the Mississippi River, the Jefferson Parish Emergency Management Department said.
The entire New Orleans metropolitan area lost power after the failure of all eight transmission lines that deliver electricity to the city, the utility company Entergy Louisiana reported.
Ida crashed ashore at a time when Louisiana is reeling from a resurgence of COVID-19 infections that has strained the state's healthcare system, with an estimated 2450 patients hospitalised statewide, many in intensive care units.
Although Ida weakened over land it still threatened to generate tornadoes in Louisiana and storm surge warnings remained in place for the Gulf coasts of Mississippi and Alabama.