The hurricane hit the Florida Panhandle as a category 4 storm.
Tolls were being suspended in the state's northwest region to ease the evacuation process, and the Florida Highway Patrol is sending almost 350 state troopers to the Panhandle and Big Bend areas, Scott said.
But hours before the storm hit, it was too late for many to flee.
Residents of the neighboring state of Georgia should also expect to be heavily impacted by the storm, the FEMA head said. According to the US Energy Information Administration.
The governors of North and SC urged residents to brace for more heavy rain and storm-force winds as Michael plows northward up the Atlantic seaboard.
Hurricane Michael has strengthened to a category two storm, with winds topping 100mph (155km/h) as it churns towards the Florida coast. An eight-foot storm surge inundated neighborhoods, covering some homes to the rooftop.
At least one person was killed when a tree crashed into his Greensboro, Florida home.
As of 3 p.m. ET on Wednesday, the hurricane's eye was approaching southeastern Alabama and southwestern Georgia.
The neighbouring state of Alabama has declared a state of emergency.
The St. Marks River overflows into the city of St. Marks, Fla., Wednesday, Oct. 10, 2018.
Manchester United keen on making January bid for Aaron Ramsey
Alexandre Lacazette and Pierre-Emerick Aubameyang scored a brace each while Aaron Ramsey was also among the scorer. It has been ten years since the Gunners signed Ramsey as a teenager from Cardiff City.
Michael battered the shoreline with sideways rain, powerful gusts and crashing waves, swamping streets and docks, flattening trees, stripped away leaves, shredding awnings and peeling away shingles.
The storm's path and the need for emergency management potentially carried political significance for Gov. Rick Scott, R, who is running for the U.S. Senate against incumbent Bill Nelson, D, and for Tallahassee Mayor Andrew Gillum, D, who is seeking to succeed Scott in a contest against Republican Ron DeSantis. "The emergency declaration is effective for seven days and makes all state resources available to local governments and entities within the impacted area of the hurricane", his office said. Forecasters said it also could bring 3 to 6 inches of rain, enough to trigger flash flooding in places still recovering from Hurricane Florence.
"We are in new territory", National Hurricane Center meteorologist Dennis Feltgen wrote on Facebook.
The storm had picked up steam as it sped across the Gulf of Mexico toward the Florida Panhandle.
"Hurricane Michael is an unprecedented event and can not be compared to any of our previous events".
Ken Graham, director of the Miami-based National Hurricane Center, said Michael is "unfortunately, a historical and incredibly risky and life-threatening situation".
Central pressure is the measure of how much the atmosphere in the middle of a storm weighs. Infrared light provides scientists with temperature data and that's important when trying to understand how strong storms can be. That's just below the threshold for a "major" hurricane.
Though wind speed is the basis for hurricane categories, central pressure is actually a better measure of damage that a hurricane will cause, a study published past year in the journal Nature Communications found.
The death, in an area west of state capital Tallahassee, was the first confirmed since Michael made landfall.
Michael sprang quickly from a weekend tropical depression, going from a Category 2 on Tuesday to a Category 4 by the time it came ashore. Based on wind speed, it was the fourth-strongest, behind the Labor Day storm (184 miles per hour, or 296 kph), Camille and Andrew in 1992.