The Sheriff's Office encouraged residents to stay indoors and off the roads.
Volunteer firefighters and the State Police later found his body downstream Thursday night. But emergency authorities lamented that many people ignored the warnings and seemed to think they could ride it out. "I have been up since 3:30 or 4 a.m. emailing and checking on staff to see if they are safe".
The department said that the fire engine had its lights and other emergency equipment activated, but roads were slick and the storm conditions were heavy. Michael's outer bands still could drop up to 3 inches of rain from New Jersey to Long Island to Cape Cod, and up to 5 inches over the MA islands of Nantucket and Martha's Vineyard through Friday afternoon, forecasters said.
Hurricane-force winds of 110mph are projected out 35 miles from the centre and tropical storm-force winds another 185 miles, putting large swathes of the southwestern U.S. in Michael's path.
Contributors in Florida include Associated Press writers Jay Reeves in Panama City, Brendan Farrington in St. Marks, Gary Fineout in Tallahassee, Tamara Lush in St. Petersburg, Terry Spencer in Fort Lauderdale, and Jennifer Kay and Freida Frisaro in Miami.
As thousands of National Guard troops, law enforcement officers and medical teams fanned out, the governor pleaded with people in the devastated areas to stay away for now because of hazards that included fallen trees and power lines.
Video from lineman Brian Kannada showed thousands of power trucks staged at the Pensacola fairgrounds until Hurricane Michael passed.
As of 5 p.m. EDT, Michael was 295 miles south of Panama City, speeding northward at 12 mph.
Tropical Storm Sergio weakened into a tropical depression Friday after soaking the Baja California Peninsula, crossing the Gulf of California and then continuing to lose punch over mainland Mexico.
Tornadoes, risky winds and more flooding are possible in numerous same areas still recovering from Hurricane Florence.
The death toll across the South stood at 13, not counting any victims in Mexico Beach. Street flooding was reported in Roanoke and other southwestern Virginia cities that reported motorists caught in flooding had to be rescued.
Florida officials said that roughly 375,000 people have been urged or ordered to evacuate.
ABC News chief meteorologist Ginger Zee said the ruins in Mexico Beach, Florida, were "eerily reminiscent to the scene I saw in Gulfport [Louisiana] in 2005", after Hurricane Katrina. Those who surveyed the damage to the towns in Michael's path said the destruction appeared to them to be more like that from a tornado, as building after building had been flattened.
One tree on Buckwalter Parkway fell onto power lines, causing two transformers to explode, resulting in scattered outages.
And in Georgia, officials in Seminole County, on the Florida border, said early Thursday that an 11-year-old girl in a mobile home was killed by a metal carport that was thrown in the air by Michael's gusting winds.
In North Carolina, a 38-year-old man was killed when a tree fell onto his vehicle as he was driving, Iredell County officials said.
"But the full extent of the damage was only slowly becoming clear, with some of the worst areas hard to reach".
Hurricane Michael's pounding waves and winds obliterated row after row of beachfront homes at ground zero on the Florida Panhandle when the epic Category 4 hurricane slammed ashore at midweek.