Many homes were ripped apart or washed away altogether in Mexico Beach, the town of 1,000 where the hurricane came ashore.
State officials said 285 people in Mexico Beach had defied a mandatory evacuation order ahead of the storm.
Though the storm has weakened, it is continuing on a unsafe path across the southeast states.
Panama City after Michael.
Catastrophic scenes have emerged across the Florida Panhandle, where Michael left more than 350,000 without power and entire neighborhoods in ruins.
General Terrence O'Shaughnessy, commander of the North American Aerospace Defense Command, said some Florida residents may have been surprised by the rapid growth of the storm.
It cut a path of destruction across the state, bringing heavy rains and damaging winds, before it entered Georgia as a Category 3 storm, the first to track into the state in over a century.
Authorities said a falling tree killed a man outside Tallahassee, Florida, and an 11-year-old girl in Georgia was killed when the winds picked up a carport and dropped it on her home. A pine tree punched a hole in their roof and he said the roar of the storm sounded like a jet engine as the winds accelerated.
In Panama City, plywood and metal flew off the front of a Holiday Inn Express.
Michael weakened as it crossed rain-soaked Georgia and moved northeast toward SC, the National Hurricane Center said.
State officials issued disaster declarations in Alabama and Georgia and the storm is also expected to bring heavy rainfall to North and SC. "I don't know the numbers yet". This carport was blown into a home killing an 11-year-old girl. Franklin County Sheriff A.J Smith told CNN that the county was almost isolated after most of the main roads were rendered impassable from flooding and downed trees.
Now a tropical storm with winds of 50 miles per hour, Michael is expected to gain strength as it passes into Virginia and moves into the western Atlantic Ocean on Thursday night, bringing damaging winds and life-threatening flash flooding over parts of North Carolina and Virginia, CNN reported. The lead-gray water was so high that roofs were about all that could be seen of many homes. We'll update this story as more information becomes available.
After Michael left the Panhandle late Wednesday, 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.
"It looks like a tornado came through here", he said.
"There are so many downed power lines and trees that it's nearly impossible to get through the city", Apalachicola Mayor Van Johnson said.
Home after home was razed from its foundations in the town of around 1,000 people. Long urged residents in the Carolinas to heed warnings and take the tropical storm seriously.
"It looks like an atomic bomb had hit our city", David Barnes, of Panama City, told the Panama City News Herald.
A Storm Surge Watch is in effect for...