NEW ORLEANS— A tropical storm that briefly grew to hurricane strength made landfall on Saturday afternoon as residents braced for a deluge of rain and high winds in strongest test to date on the city’s fragile infrastructure since Hurricane Katrina 15 years ago.

Around 11 a.m. on Saturday, the National Hurricane Center upgraded Barry to a Category 1 Hurricane. But as the storm made landfall near Intracoastal City, Louisiana, it was immediately downgraded back to tropical storm. The storm, with winds up to 70 mph, will continue to push inland and moving northwest, according to the National Hurricane Center.

Tropical storm Barry is expected to cause mass flooding and test local flood prevention efforts including levies which gave way during Katrina, destroying large swaths of the city with flood waters.

The anxiety was clear even before Hurricane Barry made landfall. Flood waters began rushing over the top of a levee in Myrtle Grove, Louisiana, which sits just south of the city not far from where the Mississippi River dumps into the Gulf of Mexico. The levee, which is located about 40 minutes outside of New Orleans, can withstand a few hours of overtopping before it breaches, Louisiana Lt. Gov. Billy Nungesser told CNN. But if the levee breaks, Nugesser said, a large part of Plaquemines Parish could face major flooding.

In preparation, the governors’ of Louisiana and Mississippi declared a state of emergency on Friday, and authorities took unprecedented precautions in closing floodgates and raising the barriers around New Orleans. Gov. John Bel Edwards told reporters Friday is the first time all floodgates have been sealed in the New Orleans-area Hurricane Risk Reduction System since Katrina.

“The real danger in the storm was never been about the wind anyway, it has always been about the rain,” he told reporters, adding that he does not expect the Mississippi River to spill over the levees despite water levels. “The levees are stronger than they have ever been. The system is tighter than it has ever been.”

By Saturday morning, residents, were already feeling the early effects of the sprawling storm just west of Morgan City, Louisiana. According to the New York Times, experts predict possible rains up to 25 inches in southern Louisiana and coastal Mississippi.

Louisiana's largest energy companies estimated the storm had already left more than 101,777 people without power as of 3 p.m. on Saturday. According to the Associated Press, the Coast Guard has rescued more than a dozen people from the flooded remote island of Isle de Jean Charles after the water had risen so high some residents were forced to take refuge on rooftops.

Heavy rains have also hit coastal Alabama, Dauphin Island Mayor Jeff Collier said on Saturday, adding that parts of his barrier island are flooded from both the driving rain and surging water from the Gulf of Mexico. The island, Collier added, still has power and minimal wind damage.

Terrebonne Parish was one of the hardest hit areas of Louisiana. Isle de Charles Jean, a remote island south of New Orleans, had become completely cut off from the mainland. At approximately 4:30 in the morning, a request for help came into the U.S. Coast Guard, which dispatched boats to Isle De Charles Jean, where they eventually rescued four residents and a cat, Coast Guard spokesperson Susan Blake told WWL TV in an interview Saturday morning.

Despite predictions that Barry would create a dangerous storm surge up the Mississippi River that could threaten the levies protecting New Orleans, by sun up Saturday it appeared the river would crest at 17 feet—three feet below the tops of the levies, and significantly lower than the tops of the city’s surge walls.

Both Uber and a Lyft had suspended their service in New Orleans Saturday morning, and all flights in and out of the city had been cancelled.

The Delta Sigma Theta sorority donated 17,000 meals to the Second Harvest Food Bank of South Louisiana after prematurely ending its national convention Friday to escape the storm. The meals, which will be stored in a cooler through the storm, will give them to residents who weather Barry, the food bank said in a Facebook post.

This is a developing story. Check back for updates.