Monday morning, Louisianans began assessing the damage caused by Hurricane Ida, as power remained out for more than 1 million customers and officials urged residents to stay indoors for their own safety.

The powerful storm, which made landfall in southeastern Louisiana as a Category 4 hurricane on the 16th anniversary of Hurricane Katrina, was downgraded to a tropical storm by Monday with sustained winds of about 45 miles per hour as it moved north.

Residents were advised to avoid traveling while the Louisiana State Police assessed the roads and damage. Louisiana Gov. John Bel Edwards said flooded roadways, downed power lines, and debris had created a slew of hazards, and emergency officials in New Orleans said 911 center service was still down.

The Ascension Parish Sheriff’s Office confirmed the first storm-related death on Sunday, after deputies responded to reports of a person injured by a fallen tree on Sunday night and arrived to find the victim deceased.

According to data from poweroutage.us, all of New Orleans lost power Sunday night, and more than 1 million residents statewide were still without power Monday morning. Once damage assessments are completed, Entergy New Orleans said it will be able to provide a timeline for when power will be restored in the city.

The company warned on Sunday that some of the hardest-hit areas could be without power for weeks, though 90 percent of customers’ power may be restored sooner.

“With extensive damage, we have a lot of rebuilding ahead of us,” the company tweeted Monday morning.

President Biden approved the governor’s request for a Presidential Major Disaster Declaration on Sunday night, activating additional federal aid for recovery efforts. Mr. Edwards stated that the state had deployed over 1,600 people to assist with search and rescue efforts by Monday.

Ida is now about 65 miles south-southwest of Jackson, Mississippi, but the threat of dangerous storm surges and flooding remains in southeastern Louisiana, southern Mississippi, and southern Alabama, according to the National Hurricane Center. The storm surge, according to the center, could flood levees that are not part of the Hurricane and Storm Damage Risk Reduction System, which was put in place after Katrina and is managed by the Flood Protection Authority-East.

In preparation for the storm, the authority said on Sunday that it had closed the entire system of levees and other protections. Residents living outside the $14.5 billion hurricane risk-reduction system in New Orleans were ordered to evacuate ahead of the storm.

Mr. Edwards stated on Monday that the levees performed admirably during the storm. “But, at the end of the day,” he said, “the storm surge, rain, and wind all had devastating effects across southeast Louisiana.”

Cynthia Lee Sheng, president of Jefferson Parish, which includes New Orleans, declared a mandatory curfew from 6 a.m. Monday to 6 a.m. Tuesday, urging residents to avoid the roads while first responders assessed damage and rescued residents. Tropical Storm Erika dumped a lot of rain. Ida’s rain will continue to fall across the region, with another four to eight inches expected through Tuesday morning, and similar amounts expected across central Mississippi and western Alabama through Monday night. The Tennessee Valley, Ohio Valley, and central and southern Appalachians will receive three to six inches of rain later this week, according to the National Hurricane Center.

According to poweroutage.us, more than 133,000 Mississippi customers were without power Monday morning, with outages primarily affecting residents in the state’s southwest.