Three additional deaths were reported in Marianna, in Jackson County, Florida, Sheriff Lou Roberts told a news conference on Friday afternoon.
The death toll from Hurricane Michael rose to 17 people across four states on Friday as rescuers, hampered by power and phone outages, used cadaver dogs, drones and heavy equipment to search devastated communities in the Florida Panhandle.
Searchers found one person dead in the rubble of Mexico Beach, said Joseph Zahralban, Miami's fire chief and the task force leader of a search and rescue unit. Three additional deaths were reported in Marianna, in Jackson County, Florida, Sheriff Lou Roberts told a news conference on Friday afternoon.
"I've watched on television, thinking of what others have experienced, like in the Carolinas and Texas," Mexico Beach Mayor Al Cathey told reporters. "But it's different when you walk down and see this, and your emotions run away. This is just a small unique coastal community."
The number of fatalities is expected to rise further as rescuers go door to door and comb through the rubble in Mexico Beach and other Florida coastal communities such as Port St. Joe and Panama City.
"I think you're going to see it climb," Brock Long, administrator of the Federal Emergency Management Agency (FEMA), said of the death count. "We still haven't gotten into some of the hardest-hit areas."
The dead include at least eight people in Florida, five in Virginia, three in North Carolina and one in Georgia.
FEMA crews have been using bulldozers and other heavy equipment to push a path through debris to allow rescuers to probe the rubble with specially trained search dogs.
Michael blew ashore near Mexico Beach on Wednesday afternoon as one of the most powerful storms in U.S. history, with winds of up o 155 miles per hour (250 km per hour). It pushed a wall of seawater inland, causing widespread flooding.
The storm, which in less than two days grew from a tropical storm to a Category 4 hurricane on the five-step Saffir-Simpson scale, tore apart entire neighbourhoods in the Panhandle, reducing homes to naked concrete foundations or piles of wood and siding.
NO PHONE, INTERNET
Except for the emergency-911 system, authorities in Bay County, the epicentre of the disaster, were virtually without telephone or internet service until late in the day on Friday, making communications internally and with the public difficult.
"We didn't have anything," said Ruth Corley, a spokeswoman for the Bay County Sheriff's Department. "We've been writing things down on pieces of paper. We're doing what we can with the minimal media that we have."
She said local television stations were knocked off the air for two days, and authorities were relying on the radio station of the Gulf Coast State College to broadcast public service bulletins.
She said search teams were going door-to-door looking for possible storm victims who may have been trapped or killed.
Bay County officials have previously said 56 people chose to stay back in Mexico Beach and search and rescue teams were trying to account for them.
Social media websites were filled with messages from people trying to reach missing family members in Florida's Bay and Gulf Counties.
Locals offered to go to addresses to see if houses had survived or if residents were there. The National Oceanic and Atmospheric Administration (NOAA) provided a website with satellite images for people to check on the condition of homes.
FEMA's Long urged communities such as Mexico Beach, where many homes were obliterated by 12 to 14 feet (3.7 to 4.3 meters) of storm surge, to rebuild to withstand future storms.
"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. "If we're going to rebuild, do it right."
By Friday morning the remnants of the storm were located about 275 miles (445 km) southwest of Nantucket, Massachusetts, with maximum sustained winds of 65 miles (100 km) per hour.
About one million homes and businesses were without power from Florida to Virginia on Friday, according to utility companies.
It could be weeks before power is restored to the most damaged parts of Florida.
The number of people in emergency shelters was expected to swell to 20,000 across five states by Friday, said Brad Kieserman of the American Red Cross. The Coast Guard reported rescuing 129 people.
Even as rescuers searched the rubble for survivors or the deceased, some residents of Mexico Beach were nervously trickling back on Friday, expressing hope the place, nicknamed "the Forgotten Coast," would not change too much as it rebuilds.
"It was the perfect beach town. Not all of that commercialism," said Dottie Sinclair, 57, a nurse, adding a Subway fast-food restaurant was the only commercial chain.
"I don't think it will ever be the same," said husband Danny Sinclair, 64, who is semi-retired. "People will just pack up and leave."