At least three people have died as a result of the storm.
Ida is barreling through Louisiana after making landfall in the state as a powerful Category 4 hurricane on Sunday afternoon.
It was one of the strongest hurricanes on record -- by both wind speed and pressure -- to roar ashore in Louisiana.
Ida, now a tropical storm, is hitting on the 16-year anniversary of Katrina, a Category 3 hurricane that ravaged the Gulf Coast. Hurricane Katrina unleashed a series of events, taking the lives of more than 1,800 people and leaving more than $100 billion worth of damage in its wake.
The mayor of Lafitte, Louisiana, is pleading for help Sunday night, saying the town needs help with water rescues. He told ABC News affiliate WGNO that 200 people were stranded.
"Never seen one like this," Mayor Tim Kerner Jr. told the station. "Worst storm in our history."
He said the storm waters are over the levees, have destroyed and school and has put people in "imminent" danger.
Ida has weakened to a Category 2 hurricane as it batters Louisiana. Six to 12 inches of rain has fallen in some parts of the state and another 4 to 6 inches is possible.
President Joe Biden has approved Louisiana Gov. John Bel Edward's request for a Presidential Major Disaster Declaration.
Ida is expected to weaken to a tropical storm Monday as it slowly moves into southwestern Mississippi with heavy rain, strong winds and flash flooding. Ida will continue to bring heavy rain through Monday across southeast Louisiana, coastal Mississippi and southwestern Alabama.
Through Wednesday, as Ida moves inland, considerable flooding is possible in parts of the lower Mississippi Valley, Tennessee Valley, upper Ohio Valley, Central Appalachians and Mid-Atlantic.
-ABC News' Melissa Griffin
Louisiana's Ochsner Health hospital system will evacuate 66 patients from two hospitals due to damaged roofs and windows, hospital officials said.
-ABC News' Matt Foster
In St. Bernard Parish, Louisiana, recovery will take months, not weeks, parish president Guy McInnis told ABC News.
Twenty-two barges in the Mississippi River broke loose from the storm. Four barges have been significantly damaged but none pose a threat to the levees, he said.
The storm surge didn't impact the levees rebuilt after Hurricane Katrina, but did damage some of the businesses in the fishing industry, he said.
-ABC News' Darren Reynolds
