Mandatory evacuation orders went into effect Tuesday morning for some 120,000 people in Panama City Beach and across other low-lying parts of the coast.
"This storm has the potential to be a historic storm, please take heed, " the sheriff's office said in the post. A few blocks inland, about half the homes were reduced to piles of wood and siding and those still standing suffered heavy damage.
Helicopters flew overhead looking for survivors as bulldozers plowed paths along roads filled with shredded homes.
Michael, the third most powerful hurricane ever to hit the USA mainland, weakened overnight to a tropical storm and pushed northeast on Thursday, bringing drenching rains to Georgia and the Carolinas, which are still recovering from Hurricane Florence last month.
The death toll from hurricane Michael, one of the most powerful storms to make landfall in the U.S. mainland, rose to six, with authorities warning that the toll could further increase as search and rescue efforts continue.
"For North Carolina, Michael isn't as bad as Florence, but it adds unwelcome insult to injury, so we must be on alert", Gov. Roy Cooper said.
Gulf Coast Regional Medical Center in hard-hit Panama City, 20 miles (32 km) northwest of Mexico Beach, was treating some of the injured.
In Panama City, buildings were crushed, tall pine trees were sent flying and a steeple was knocked off a church.
At the city's Jinks Middle School, the storm peeled back part of the gym roof and tore off a wall.
A Hurricane Warning is still in place in coastal Bay County, Florida.
Disaster agencies in El Salvador, Honduras and Nicaragua reported 13 deaths as roofs collapsed and residents were carried away by swollen rivers. "Roofs are gone", Principal Britt Smith told CNN after talking by phone with those who did not evacuate. "I have been up since 3:30 or 4 a.m. emailing and checking on staff to see if they are safe".
Almost 950,000 homes and businesses were without power in Florida, Alabama, the Carolinas and Georgia on Thursday. An estimated 6,000 people evacuated to emergency shelters, mostly in Florida, and that number was expected to swell to 20,000 across five states by week's end, said Brad Kieserman of the American Red Cross.
The rescue came just hours after Hurricane Michael ripped through Florida's Panhandle, almost wiping out Panama City and Mexico Beach.
Michael pummelled communities across the Panhandle and turned streets into roof-high waterways.
"If you decide to stay in your home and a tree falls on your house or the storm surge catches you and you're now calling for help, there's no one that can respond to help you, " Mr Morgan said at a news conference.
"Michael is likely to produce potentially catastrophic wind damage where the core of the hurricane moves onshore in the Florida Panhandle, and everyone in the hurricane warning area should prepare for life-threatening hurricane winds".
The Gulf of Mexico is home to 17 percent of daily U.S. crude oil output and 5 percent of daily natural gas output, according to the U.S. Energy Information Administration.
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