Originally Published: 30 AUG 21 00:19 ET

Updated: 30 AUG 21 13:49 ET

By Jason Hanna and Madeline Holcombe, CNN

(CNN) -- Hurricane Ida has left catastrophic damage across southeastern Louisiana, killing at least one person, leaving much of the New Orleans area without power, interrupting phone service and sending rescuers scrambling Monday to flooded homes where people were anxiously asking for help.

Ida, now a slow-moving tropical storm over western Mississippi, still threatens to cause more flooding not just in the Deep South but also into the Tennessee and Ohio valleys as it crawls north over the next few days.

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Rescuers are getting numerous reports of people who've climbed into attics or onto roofs as waters rose in their homes, especially in parishes just outside New Orleans.

About 15 people were helped off roofs and into boats early Monday in the city of Slidell alone, and rescuers in high-water vehicles still were taking people to safety in the lower side of town in the late morning, Mayor Greg Cromer said.

Because cell phone service is sporadic in much of the region, rescuers sometimes are having to find for themselves who needs help.

"We've had some people that ... wadded out (of neighborhoods) and flagged police officers down and told us what is going on," Cromer, mayor of the city northeast of New Orleans, told CNN on Monday morning.

"Seems like there's hundreds, possibly more, people trapped in their houses, with some extent of water -- from a foot deep to people in the attics," Jordy Bloodsworth, fleet captain of the Louisiana Cajun Navy volunteer rescue group, told CNN earlier Monday morning.

Bloodsworth was sending his teams to LaPlace, in St. John the Baptist Parish just west of New Orleans, where the National Weather Service and posts on social media have indicated numerous people have asked for rescue.

In LaPlace, Tiffany Miller was stuck in her attic Sunday night after floodwaters came into her home, she said. Perhaps 3 to 5 feet of water had entered homes in her subdivision, she told CNN affiliate WDSU.

"When we got in the attic, the water was right below my knees," Miller said. "I know that we're not in it by ourselves, and it's going to be OK."

Paul Middendorf, volunteering with the Crowdsource Rescue group, paddled solo through LaPlace in a canoe and ferried dozens of people Monday from their flooded homes, he said.

"Most of (the rescues) were in the attic," he said. "The water in the back of that neighborhood was about 10 feet deep or higher."

The United Cajun Navy, a separate volunteer rescue group, made more than 300 rescues by noon Monday, including in Houma, a roughly 60-mile drive southwest of New Orleans, Todd Terrell, the group's president, said.

In lower Lafitte south of New Orleans, people reportedly are on roofs, pleading for help as water is nearly reaching to the rooftops, Jefferson Parish President Cynthia Lee Sheng told CNN Monday morning.

"Right now the focus is on preserving life, and finding those folks and saving them," she said.

Residents also were forced to their roofs in the nearby town of Jean Lafitte, Mayor Tim Kerner Jr. said, as levees were overtopped there.

Louisiana State Police warned Monday that communication limits and debris-clogged roads may delay help to stranded residents "for quite some time."

Governor 'fully expects the death count will go up'

Ida made landfall Sunday near southeastern Louisiana's Port Fourchon as a Category 4 hurricane around 1 p.m. and slowly scraped across the state, delivering catastrophic winds and torrential rains to the same places for hours.

Video from these areas showed parts of roofs flying off homes and businesses, fallen trees lying on cars and homes, and high water taking over roads and communities in southeastern Louisiana and southern Mississippi.

In hard-hit Houma, some buildings were leveled, and others were missing pieces of roofing.

Lionel Hawkins and his wife stayed in their Houma house as the storm hit; it sounded bad, so they got down on their knees and prayed, he said.

"Went down and got on a knee and asked the Lord ... to protect us. Give us another opportunity to breathe," Hawkins told CNN Monday. His home still stands, though the roof is damaged and the carport was blown apart.

Gov. John Bel Edwards urged residents to check on their neighbors but otherwise refrain from traveling Monday morning because of flooded roadways, debris and downed power lines.

Edwards "fully expects the death count will go up considerably throughout the day" as searches and rescues go on, he told MSNBC on Monday.

"We know that individuals are out there waiting to be rescued because their homes are not habitable ... please know that we have thousands of people out right now with high water vehicles and boats who are doing search and rescue," the governor said in a video posted on Twitter.

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Ida slammed into Louisiana on the 16th anniversary of Hurricane Katrina, tying with 2020's Hurricane Laura and the Last Island Hurricane of 1856 as the strongest ever to hit the state.

More than 1 million customers in Louisiana were without power Monday morning, according to PowerOutage.US -- including all of New Orleans, which was hit with "catastrophic transmission damage," the city office tweeted Sunday night. More than 110,000 customers were without power in Mississippi, PowerOutage.US reported.

Entergy Louisiana said some of its customers could be without power for weeks. New Orleans City Councilmember Joe Giarrusso conceded any sooner would be optimistic, given that it took weeks to restore power to some areas after last year's Category 4 Hurricane Laura hit the state.

Without power for things such as air conditioning in the summer heat, the power outages could be deadly, Giarrusso said.

In New Orleans on Monday, resident Judy Arabie surveyed her neighborhood, where a utility pole and transformer had fallen onto a car. During the storm, part of her roof was torn open -- and she couldn't sleep as the storm went through overnight.

"Last year we had (Hurricane) Zeta, and electricity was out for about five days, but it was nothing compared to this -- the winds, the gusts, the shingles flying everywhere," Arabie said.

In part of Plaquemines Parish southeast of New Orleans, flash flooding was reported early Monday morning after a levee failed near Highway 23, according to the National Weather Service.

Authorities were rushing to evacuate people in the Jesuit Bend area there as water rushed up the highway, Louisiana Lt. Gov. Billy Nungesser said Monday.

'This is turning into a rainmaker'

Ida will threaten more flooding Monday in the Deep South and elsewhere as it marches north over the next few days. Numerous counties and parishes were under flash flood warnings in parts of Louisiana, Mississippi, and Alabama on Monday morning.

"It's the rainfall that we're worried about now. This is turning into a rainmaker," CNN meteorologist Chad Myers said Monday morning.

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Another 4 to 8 inches of rain could fall Monday in parts of Louisiana and Mississippi, bringing storm totals there to 10 to 24 inches, the National Hurricane Center said.

The storm is expected to turn northeast Monday and head to the middle Tennessee Valley and Upper Ohio Valley through Wednesday.

The Tennessee Emergency Management Agency advised residents across the state Sunday to prepare for Ida, warning that heavy rain and flooding are possible in areas still recovering from a flood emergency last weekend.

Coastal Alabama to the far western Florida Panhandle could get storm totals of 6 to 15 inches of rain through Tuesday. Central Mississippi to far western Alabama could get 4 to 12 inches of rain through Monday.

Other areas, including the Middle Tennessee Valley, Ohio Valley, the central and southern Appalachians and the Mid-Atlantic, could generally receive 3 to 6 inches of rain through Wednesday, the hurricane center said.

Hospitals damaged and roadways closed

President Joe Biden granted Edwards' request for a major disaster declaration, ordering federal agencies Sunday night to supplement state and local recovery efforts.

Resources to help those affected by the storm have been impacted, with hospital staff relying on generators to keep life-saving machines running and sleeping on air mattresses in their workplaces.

Hospitals dealing with storm damage and attending to victims of the hurricane were largely already stretched by the Covid-19 pandemic.

"Before going into this storm, our hospital was already almost at capacity," Ochsner Health System's Dr. Derek Smith told CNN. "We know the coming hours are going to be even more of a test."

The hospital is running on generators, and staff there have been locked in -- sleeping on air mattresses and working around the clock to care for patients, Smith said.

In Lafourche Parish southwest of New Orleans, two of the three hospitals sustained damage in Sunday's storm, parish Sheriff Craig Webre told CNN.

A portion of the roof of The Lady of the Sea General Hospital in Galliano was ripped off as Ida came ashore, Webre told CNN. The county was also forced to relocate its emergency operations center to a different building after the first building's roof began to leak Sunday, Webre told CNN.

Every road in Lafourche Parish was impassible Sunday night, Webre told CNN.

And because of fallen trees, the Louisiana Department of Transportation and Development shut down about 22 miles of Interstate 10, a major thoroughfare that transits the state east to west.