(PANAMA CITY, Fla.) -- At least one person has died as a result of Hurricane Michael, a monstrous storm that made landfall Wednesday afternoon as a Category 4 with top winds of 155 mph.
Michael is the strongest storm since Hurricane Camille in 1969 and the third most powerful ever on record to hit the U.S.
A broad swath of the Southeast is affected, with about 20 million people under either a warning or a watch for the hurricane, flooding or tornadoes, said ABC News contributor Tom Bossert, former Homeland Security Adviser to President Donald Trump.
"Hurricane Michael is the worst storm that the Florida Panhandle has ever seen," Gov. Rick Scott said in a press conference Wednesday evening.
The victim of the storm died in a "debris-related" incident in Greensboro, about 30 miles west of Tallahassee, Olivia Smith, public information for the Gadsden County Sheriff's Office, told ABC News.
After making landfall early Wednesday afternoon, the storm tore through northwest Florida. By 4 p.m., Michael still had extreme winds of 140 mph as it moved inland toward southwest Georgia. The eye of the storm was moving through southwestern Georgia around 6 p.m.
Although the storm system passed quickly through the state, Scott urged people to continue to shelter due to forecasts predicting that the life-threatening storm surge and damaging winds will continue.
"The worst thing you can do now is act foolishly or put yourself and your family at danger," Scott said.
Nearly 400,000 customers in Florida were without power as of Wednesday evening, according to state data. In Alabama, more than 60,000 customers were without power.
A dangerous tropical event with strong winds and very heavy rain is expected for parts of Georgia Wednesday night, and the tropical storm conditions will then spread across Georgia and the Carolinas overnight through Thursday.
Life-threatening winds, dangerous storm surge
As the winds pushed the ocean water onto the coast of Mexico Beach, Florida, ABC News chief meteorologist Ginger Zee said she saw an "entire home, a well-built home, rolling down the street. ... it makes you shake."
Unlike last month’s Hurricane Florence which brought massive flooding to the Carolinas, one of the biggest threats from Michael is the wind.
Michael -- described by Florida Gov. Rick Scott as "monstrous" -- made landfall with almost the highest wind speed possible for a Category 4 -- 155 mph. When a hurricane reaches 157 mph, it is in the highest category, a Category 5.
After Michael barrels through Florida, it may strike Georgia as a Category 2, according to FEMA.
As Michael approached the coast its pressure dropped to about 919 millibars (mb).
The lower the pressure, the more intense the storm. Hurricane Katrina in 2005 made landfall with a pressure of 920 millibars.
The hurricane also was forecast to bring a storm surge of up to 14 feet high, prompting warnings from officials.
"Anybody that doesn't evacuate that experiences storm surge doesn't typically live to tell about that story," Brock Long, administrator of the Federal Emergency Management Agency, told "Good Morning America" on Wednesday.
Residents seek shelter, hunker down
Thousands fled the Florida coastline before the heavy rain -- which may reach up to 12 inches -- began.
But by Wednesday morning, it was too late to evacuate. Those who remained were urged to shelter in place.
"This was a shock waking up knowing it was a [Category] 4," said Panama City Beach resident Julie Gordon. "Thinking it was a [Category] 2 was a very different story."
All bridges from Panama City Beach to further inland have closed, so Gordon said she is riding out Michael at home, "hoping and praying that the storm will continue to drift to the northeast ... [an area] where it's not quite as populated."
The Panhandle is the wide strip of northwest Florida with the Gulf of Mexico to the south and Alabama and Georgia to the north. Popular with tourists for its beaches, the area also has many year-round residents -- its largest city is Pensacola, with a population approaching half a million.
About 4,000 people have entered 70 evacuation shelters, FEMA officials said.
Michael may bring weekslong power outages, officials added.
Bossert said he's concerned not enough people evacuated and many rescues may be needed after the brunt of the storm passes.
"I am very, very worried" about the recovery, Bossert added. "People are going to really struggling after this one."
Mobile homes are especially a concern since they aren't built to withstand hurricane-force winds, so in one county in south Georgia, mobile home residents were invited to shelter at a local church, reported ABC affiliate WALB in Albany, Georgia.
"The size of this thing is growing," said Reggie Rachals, sheriff of Lee County, Georgia. "It will tear up mobile home parks real bad."
States of emergency across the South
Scott declared a state of emergency in 35 counties in Florida. Trump approved an emergency declaration for Florida, permitting the federal government to provide resources and aid during the dangerous storm.
"This is a small storm in an area that they never thought that it would be, and they said it grew into a monster," Trump said Wednesday from the Oval Office.
"We're very, very prepared," the president said. "We have massive amounts of food and water that gets brought in immediately."
Trump said, "It is not so easy" for some residents to evacuate.
"Some of the areas are very poor. Not easy for a person without the necessary money to leave," he said.
Despite the storm, Trump said he plans to still attend his Wednesday night rally in Pennsylvania, telling reporters, "You have so many people already there and it’s sort of unfair to them."
He added that he will likely visit Florida on Sunday or Monday.
After tearing through Florida, Michael headed toward Georgia, where Gov. Nathan Deal had declared a state of emergency.
"What you're going to see is a storm moving very rapidly through Georgia, and it will maintain hurricane strength through southwest Georgia and central Georgia as it passes through later today and early tomorrow," FEMA's Long told "GMA" on Wednesday morning.
In Alabama, where residents may see massive power outages, high winds and heavy rain, Gov. Kay Ivey issued a state of emergency.
North Carolina and South Carolina will likely see heavy rainfall, which could cause flooding in areas already damaged and rain-soaked by last month’s Hurricane Florence.
A state of emergency was declared Wednesday in North Carolina, said Gov. Roy Cooper, as he warned that winds will be strong enough to down trees.
The last Category 4 hurricanes to strike the U.S. mainland were both in 2017 -- Irma, which slammed into Florida, and Harvey, which hit Texas.
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