The 400-mile-wide storm came ashore with 155 mph winds, making it the strongest to hit the U.S. in nearly half a century.
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On Tuesday, NASA shared what the storm looked like when it was still in the Gulf of Mexico.
Hurricane Michael from space: Video shows powerful, massive storm seen from International Space Station
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By the time it made landfall in Florida's Panhandle, the storm had reached historic strength.
Local news reporters were working in the dark. At the Panama City news station WJHG/WECP, reporter Tyler Allender tweeted that his colleagues were taking shelter in a hallway in the middle of the building because "this wind is SERIOUS."
Allender said they were sitting in the dark because their building had lost power.
The storm is expected to quickly move north along the East Coast in the next few days.
PHOTOS: Hurricane Michael lashes Florida
A man walks through the damaged historical downtown district in the aftermath of Hurricane Michael in Panama City, Fla., Friday, Oct. 12, 2018.none
A woman walks past a damaged building in the historical downtown district in the aftermath of Hurricane Michael in Panama City, Fla., Friday, Oct. 12, 2018.none
The aftermath of Hurricane Michael in Marianna, Fla. on October 11, 2018.none
A ship is seen capsized after category 4 Hurricane Michael made land fall along the Florida panhandle Wednesday, on Thursday, Oct. 11, 2018 in Panama City, FL.none
Benny Hobson, 69, sits in his recliner after loosing the front wall of his house after Hurricane Michael. Hobson rode the storm at his home with his wife and three dogs.none
Power lines and trees cover streets after category 4 Hurricane Michael made land fall along the Florida panhandle Wednesday, on Thursday, Oct. 11, 2018 in Panama City, FL.none
A home is destroyed from Hurricane Michael Thursday, Oct. 11, 2018, in Mexico Beach, Fla.AP
Debris from Hurricane Michael fills a lot Thursday, Oct. 11, 2018, in Mexico Beach, Fla.AP
Homes destroyed by Hurricane Michael are shown in this aerial photo Thursday, Oct. 11, 2018, in Mexico Beach, Fla.AP
A roof over a boat storage building is collapsed following Hurricane Michael Thursday, Oct. 11, 2018, in Panama City Beach, Fla.AP
Debris from homes destroyed by Hurricane Michael block a road Thursday, Oct. 11, 2018, in Mexico Beach, Fla.AP
Michael Williams, 70, waves to passing motorists while looking for food and water in the aftermath of Hurricane Michael in Springfield, Fla.AP
A woman walks through a damaged store in the aftermath of Hurricane Michael in Springfield, Fla., Thursday, Oct. 11, 2018.AP
Storm damage is seen in a bathroom that lost its roof in the aftermath of Hurricane Michael October 11, 2018, in Panama City, Florida.Creative Content
Storm damage is seen in the aftermath of Hurricane Michael October 11, 2018, in Panama City, Florida.Creative Content
A man works through the remains of an apartment in the aftermath of Hurricane Michael October 11, 2018, in Panama City, Florida.Creative Content
Storm damage is seen in the aftermath of Hurricane Michael October 11, 2018, in Panama City, Florida.Creative Content
People walk amidst destruction on the main street of Mexico Beach, Fla., in the aftermath of Hurricane Michael on Thursday, Oct. 11, 2018.none
Mishelle McPherson looks for her friend in the rubble of her home, since she knows she stayed behind in the home during Hurricane Michael, in Mexico Beach, Fla., Thursday, Oct. 11,none
A boat sits amidst debris in the aftermath of Hurricane Michael in Mexico Beach, Fla., Thursday, Oct. 11, 2018.none
Rescue personnel perform a search in the aftermath of Hurricane Michael in Mexico Beach, Fla., Thursday, Oct. 11, 2018.none
Joyce Fox, center stands in front of her heavily damaged home in the aftermath of Hurricane Michael in Panama City, Fla., Thursday, Oct. 11, 2018.none
Derailed box cars are seen in the aftermath of Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.none
Derailed box cars are seen in the aftermath of Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.none
An American flag battered by Hurricane Michael continues to fly in the in the rose colored light of sunset at Shell Point Beach on October 10, 2018 in Crawfordville, Florida.none
A car is seen caught in flood water after category 4 Hurricane Michael made land fall along the Florida panhandle, on Wednesday, Oct. 10, 2018 in Panama City, FL.none
Television reporters stand watching as category 4 Hurricane Michael makes land fall along the Florida panhandle, on Wednesday, Oct. 10, 2018 in Panama City Beach, FL.none
A Booze Express is seen damaged after category 4 Hurricane Michael made land fall along the Florida panhandle, on Wednesday, Oct. 10, 2018 in Panama City Beach, FL.none
A woman crosses a flooded street after Hurricane Michael made landfall on October 10, 2018 in Panama City, Florida.none
Tamiya Waldon looks out at the damage to her neighborhood in the aftermath of Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.AP
A man walks in the street of his heavily damaged neighborhood in the aftermath of Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.AP
Dorian Carter looks under furniture for a missing cat after several trees fell on their home during Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.AP
Megan Williams, left, and roommate Kaylee O'Brian take belongings from their destroyed home after several trees fell on the house during Hurricane Michael.AP
Carol Ralph walks through downed trees blocking her heavily damaged neighborhood just after Hurricane Michael passed through in Panama City, Fla., Wednesday, Oct. 10, 2018.AP
People walk through downed trees in a heavily damaged neighborhood in the aftermath of Hurricane Michael in Panama City, Fla., Wednesday, Oct. 10, 2018.AP
Pam Heckstall surveys the damage as the remnants of Hurricane Michael move through Panama City, Fla., Oct. 10, 2018. She is not able to leave her street due to downed trees.AP
People look on at a damaged store after Hurricane Michael passed through on October 10, 2018, in Panama City, Florida.Creative Content
Storm damage is seen after Hurricane Michael October 10, 2018, in Panama City, Florida.Creative Content
Damaged boats and a truck are seen in a marina after Hurricane Michael October 10, 2018, in Panama City, Florida.Creative Content
A McDonald's sign is seen laying on the ground after it was knocked down by hurricane Michael as it passed through the area on October 10, 2018, in Panama City, Fla.Creative Content
Jane Lindsey looks through the front display to her antique shop after its window was shattered during Hurricane Michael October 10, 2018, in Panama City, Florida.Creative Content
A view of storm damage during Hurricane Michael October 10, 2018, in Panama City, Florida.Creative Content
A store's windows are seen shattered as hurricane Michael passed through the downtown area on October 10, 2018, in Panama City, Florida.Creative Content
A house is seen with damage to its roof and downed trees during Hurricane Michael October 10, 2018, in Panama City, Florida.Creative Content
Downed power lines are seen after hurricane Michael passed through the downtown area on October 10, 2018, in Panama City, Florida.Creative Content
An electric transformer explodes in the distance as heavy rains and wind from Hurricane Michael blanket the Florida State University campus Wednesday, Oct. 10, 2018.AP
A hotel employee holds a glass door closed as it breaks from flying debris during Hurricane Michael in Panama City Beach, Fla., Wednesday, Oct. 10, 2018.AP
Hotel employees look at a canopy that just collapsed, as Hurricane Michael passes through in Panama City Beach, Fla., Wednesday, Oct. 10, 2018.AP
A storm chaser films from underneath a hotel canopy during Hurricane Michael in Panama City Beach, Fla., Wednesday, Oct. 10, 2018.AP
A hotel canopy collapses onto vehicles during Hurricane Michael in Panama City Beach, Fla., Wednesday, Oct. 10, 2018.AP
A storm chaser climbs into his vehicle during the eye of Hurricane Michael to retrieve equipment after a hotel canopy collapsed in Panama City Beach, Fla., Oct. 10, 2018.AP
A woman checks on her vehicle as Hurricane Michael passes through, after the hotel canopy had just collapsed, in Panama City Beach, Fla., Wednesday, Oct. 10, 2018.AP
Sean Pelham holds his daughter Sophia, 2, in a hallway at an evacuation shelter set up at Rutherford High School in advance of Hurricane Michael.none
Cameron Sadowski walks along where waves are crashing onto the beach as the outer bands of hurricane Michael arrive on October 10, 2018 in Panama City Beach, Florida.none
The storm surge and waves from Hurricane Michael batter the beachfront homes on October 10, 2018 in the Florida Panhandle community of Shell Point Beach, Florida.none
Pets are seen as people seek safety in a shelter as Hurricane Michael approaches on October 10, 2018 in Panama City, Florida.none
Emily Hindle lies on the floor at an evacuation shelter set up at Rutherford High School, in advance of Hurricane Michael on Wednesday.none
The St. Marks River overflows into the city of St. Marks, Fla., ahead of Hurricane Michael, Wednesday, Oct. 10, 2018.none
Jayden Morgan, 11, evacuates his home as water starts to flood his neighborhood in St. Marks, Fla, ahead of Hurricane Michael.none
The St. Marks River overflows into the city of St. Marks, Fla., ahead of Hurricane Michael, Wednesday, Oct. 10, 2018.none
Waves crash along a pier as the outerb ands of hurricane Michael arrive on October 10, 2018 in Panama City Beach, Florida.none
Carol Cathey spray paints the words 'Calm down Michael' on the plywood over her daughter's business on October 9, 2018 in Mexico Beach, Florida.none
These empty shelves were spotted on Tuesday in Fort Walton Beach, Florida.none
''Davidson Middle School in #Crestview has opened its doors as a shelter,'' the Okaloosa Co. Sheriff's Office wrote on Twitter.none
Hurricane preparations were underway on Tuesday, Oct. 9 in Pensacola, Florida.none
Stores were boarded up in Panama City, Floria, on Tuesday, Oct. 9.none
One Twitter user took a photo of the water bottle aisle in Winn Dixie in Panama City, Florida earlier in the week.none
''RE: #HurricaneMichael ...Tallahassee got the memo!'' wrote one Twitter user at a store with empty shelves.none
A tourist attraction is seen with its doors boarded up to offer protection from Hurricane Michael October 9, 2018 in Panama City Beach, Florida.none
The Associated Press contributed to this report.