Almost 800 rescued in St. John the Baptist Parish after Hurricane Ida

Ida remained a strong Category 4 hurricane at 3 p.m., with maximum sustained winds of 145 mph.

The center of the storm is currently 25 miles west-northwest of Grand Isle, Louisiana, after making a second landfall along the southeastern Louisiana coast, just southwest of Galliano.

The eye of the storm is continuing to come ashore, bringing powerful, damaging winds and torrential rain.

Extreme wind warnings have now been issued over an extended area, southwest of New Orleans.

A recent wind gust of 76 mph was reported at New Orleans Lakefront Airport, while wind gusts of 125 mph were reported at Golden Meadow, Louisiana. Winds are also gusting more than 115 mph in places like Houma, Thibodaux, Laplace and Gramercy.

Storm surge up of 7.2 feet is coming into Shell Beach, Louisiana, while 6.3 feet of surge was reported in Waveland, Mississippi.

Tornado watches are in effect in coastal parts of Louisiana, Mississippi, Alabama and Florida.

The heavy rain and flash flooding threats will eventually reach the Tennessee Valley Monday into Tuesday and will likely affect Waverly, Tennessee, which was recently devastated by deadly flooding.

-ABC News’ Melissa Griffin and Dan Peck

More than 223,000 customers without power in Louisiana as Hurricane Ida moves through the state, according to poweroutage.us.

-ABC News' Will McDuffie

Hurricane Ida is holding on to maximum sustained winds of 150 mph more than an hour after it made landfall near Port Fourchon, Louisiana.

As Ida’s eye continues to move ashore, it is bringing powerful, damaging winds, torrential rain and dangerous storm surge to the southeast Louisiana coast.   

The center of the storm is currently about 55 miles south-southwest of New Orleans and is moving northwest at 13 mph.

Ida will continue to move across southeastern Louisiana through Sunday afternoon, bringing major weather impacts to a widespread region.

Relentless heavy rain could trigger potentially significant flash flooding, while high wind gusts, dangerous storm surge and possible tornados also threaten the area.

Tornados are also possible in parts of Louisiana, Mississippi, Alabama and the Florida panhandle.

Storm surge concerns will be greatest Sunday afternoon and evening as the storm moves further inland. The surge could reach 8 to 12 feet in some spots along the coast of Louisiana and Mississippi.

An extreme wind warning remains in effect for the region, including in Grand Isle, Louisiana, which is currently reporting intense wind gusts.

Deteriorating conditions with heavy rounds of rain and possible flash flooding are expected in New Orleans over the next few hours.

The system will begin to weaken over the next few hours but will still bring dangerous hurricane conditions over a widespread area. A large swath of the Louisiana and Mississippi areas can see 10 to 20 inches.

The heavy rain and flash flooding threats will eventually reach the
Tennessee Valley Monday into Tuesday.

-ABC News’ Dan Peck

Residents who did not evacuate storm-affected regions of Louisiana are being instructed to shelter in place, as conditions are now too perilous for first responders to save them.

"There’s nobody coming right now," said New Orleans Director of Homeland Security Collin Arnold Amayor during a press conference Sunday afternoon. "You need to stay inside."

People have even been instructed to avoid going to hospitals, which are hunkering down amid the life-threatening winds and heavy rain.

"Please do not try to access a health care or hospital facility right now," said Jennifer Avegno, director of the New Orleans Health Department. "Our hospitals are hunkering down. They are caring for the patients who are within their walls…We will be there for you when the storm passes."

-ABC News’ Joshua Hoyos and Will McDuffie