With winds as high as 155 miles per hour, Michael leveled buildings and structures, flooded streets, and left a trail of destruction.
The storm is the first hurricane of this intensity to strike the area since records began in 1851 and the third most powerful to ever strike the US.
Gov. Rick Scott said search and rescue efforts would be "aggressive".
"I've worked most of my adult life out of town..."
An estimated 6,000 evacuees took cover in emergency shelters, a lot of them in Florida, and that number was expected to swell to 20,000 across five states by week's end, Kieserman said.
The full extent of Michael's fury was only slowly becoming clear, with some of the hardest-hit areas difficult to reach because of roads blocked by debris or water.
Entire blocks of homes near the beach were obliterated, leaving concrete slabs in the sand.
Much of the affected area is rural and known for small tourist cities, beaches and wildlife reserves, as well as the state capital, Tallahassee, home to about 190,000 people.More news: 6 extremely surreal moments from Kanye West's meeting with President Trump
Twenty miles south of Mexico Beach, floodwaters were more than seven feet deep near Apalachicola, a town of about 2,300 residents, hurricane center chief Ken Graham said.
We're sending positive thoughts to the Gulf Coast and others in Micheal's path.
Mishelle McPherson and her ex-husband looked for the elderly mother of a friend on Thursday.
He added that his 12-year-old son witnessed "the whole thing".
Late yesterday Corelogic pegged the wind and storm surge insurance industry loss at up to $4.5 billion, although this was a pre-landfall assessment so did not factor in how the storm tracked after landfall. She's desperate for news about the condition of her home, but she can't reach anyone, she says. "It was very bad, and now there's just nothing left". It's left hundreds of thousands of people without power and an untold number of people homeless.
"I think you're going to see it climb", FEMA Administrator Brock Long said of the death count at a news conference.
"It's OK if you want to live on the coast or on top of a mountain that sees wildfires or whatever but you have to build to a higher standard", he said.
Nearly 1.2 million homes and businesses were without power from Florida to Virginia on Thursday because of the storm.
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Rob Golding has opened his home in the Springfield Callaway suburb of Panama City to some of his neighbors whose homes were heavily damaged.
In Panama City, most homes were still standing, but no property was left undamaged. Roofs had been peeled off.
Kaylee O'Brien was crying as she sorted through the remains of the apartment she shared with three roommates at Whispering Pines apartments, where the smell of broken pine trees was thick in the air. Others were missing roofs or walls.
They plan to use remote sensing and geotag photo technology to assess damage and update residents in real time.
Even before landfall, the hurricane disrupted energy operations in the Gulf, cutting crude oil production by more than 40 per cent and natural gas output by almost a third as offshore platforms were evacuated ahead of the storm's arrival.
A falling tree also killed an 11-year-old girl in her home in southwest Georgia, according to local media reports. A driver in North Carolina was killed when a tree fell on his vehicle.
Trump, who is expected to visit the region as early as Sunday, said he would be "totally focused" on the storm but would not cancel a Wednesday night campaign rally in Pennsylvania. More than 6 inches of rain has fallen in the western part of the state, Cooper said.
In North Carolina's mountains, drivers also had to be plucked from cars in high water.More news: Tony Ferguson Defeats Anthony Pettis In A World-Class Fight Via TKO!