(CNN) -- From building-crushing hurricanes to killer sinkholes, Gulf Coast residents have seen a lot. But even these battle-tested veterans of the weather wars are marveling at torrential rains that washed out bridges and roads, sent chest-high water into homes and forced major military bases to shut down Wednesday.
"We've seen flooding before, but never flooding that washes the back of a house away," said CNN iReporter Matt Raybourn of Pensacola, Florida. "There are no words for what we are seeing here."
The rushing waters reduced some streets to rubble, gouged huge gashes in others and left stretches of many others submerged, including parts U.S. Highway 98, the main east-west route along the coast. It was closed in several places between Fort Walton Beach and Panama City. Abandoned cars sat half-submerged along the highway.
Along the coast, water pushed ashore by wind-driven waves and unusually high tides lapped at sand dunes as red flags warned swimmers to stay out of the water.
The Florida Highway Patrol reported one drowning death associated with the flooding. Details weren't immediately available.
In a neighborhood north of Pensacola, a creek overran its banks, inundating homes and forcing residents to retreat to their attics to await rescue, Escambia County spokesman Bill Pearson said.
Rescuers were reaching the residents on state Fish and Wildlife boats and personal watercraft normally used to patrol the county's beaches, he said. The National Guard was also on the way.
Gov. Rick Scott said Wednesday morning that crews had completed more than 200 rescues out of 300 requests for help in the state. He declared a state of emergency and warned residents to expect more rain and flooding.
As much as 18.9 inches of rain fell over 24 hours in Alabama and Florida, according to the National Weather Service.
It was all the result of a slow-moving and massive storm system that sucked up moisture from the Gulf of Mexico for days before dumping it back onto land in a series of thunderstorms, said CNN meteorologist Jennifer Gray. Satellites captured an image of the water vapor held aloft by the storm tracing a huge sideways 'S' shape across much of the country.
In Perdido Key, Florida, iReporter Steve Olensky described the storm as a "hurricane and tornado all in one." "It was blowing and blowing, the rain was coming. It was just incredible," said Olensky, whose 22-foot boat vanished in the storm. "We've been through (hurricanes) Ivan and Katrina, and we've never seen anything like this."
Many roads in the city of Gulf Shores, Alabama, were "totally flooded," the city said on Twitter. At least three heavily used bridges in Escambia County, Florida, had been badly damaged or destroyed, said Pearson, the county spokesman.
Naval Air Station Pensacola, Eglin Air Force Base and Hurlburt Field, another Air Force installation, were closed to all but essential personnel, the installations said on their Twitter and Facebook accounts.
In nearby Baldwin County, Alabama, the Fish River reached historic flooding levels, according to the National Weather Service.
Most government offices in the Florida Panhandle were closed Wednesday, as were many schools. Pearson said emergency officials were urging businesses to stay closed as well and were asking motorists to stay off the roads.
Tides up to 2 feet higher than normal were causing minor coastal flooding and dangerous rip currents, the National Weather Service said.
CNN iReporter Randy Hamilton said the scene felt like the aftermath of a hurricane with "abandoned and flooded cars just littering the streets."
"Debris from trees everywhere. Standing water all around, gray skies, and wind gusts that make you fear something will blow down on you," he said.
The storms were part of the same system that has spawned tornadoes and other severe storms since Sunday, claiming at least 36 lives in Oklahoma, Iowa, Arkansas, Mississippi, Alabama, Tennessee and now Florida.
Tens of thousands remained without power in the South, where suspected tornadoes tore through homes and businesses late Monday.
In addition to the Florida flooding death, police in Athens, Georgia, said a driver was killed Wednesday when storm winds toppled a tree onto a car. At least 17 people died because of storms in Mississippi, Alabama and Tennessee on Monday. Those deaths are in addition to 18 others reported from storms Sunday in Arkansas, Oklahoma and Iowa.
Search and rescue efforts were still under way in Louisville, Mississippi, about 90 miles northeast of Jackson, where a tornado flattened a day care center, said Robert Latham of the Mississippi Emergency Management Agency.
Mississippi Gov. Phil Bryant said the twisters inflicted "severe damage" in Louisville. Winston Medical Center, Louisville's major hospital, was also among the buildings hit.
The storm could bring heavy rains and possibly thunderstorms to places like Jacksonville, Florida; Charlotte, North Carolina; Virginia Beach, Virginia; Raleigh, North Carolina; and Atlanta, the National Weather Service said.
Heavy rain will be the norm.
CNN's Wolf Blitzer, Martin Savidge, Ed Payne, Chad Myers, Tina Burnside, Jill Martin, John Helton, Sean Morris, Christina Zdanowicz and Suzanne Presto contributed to this report.
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