By Ray Sanchez, Nicole Chavez, Steve Almasy and Doug Criss, CNN

(CNN) -- At least one death was reported Saturday as Texans who rode out the most powerful hurricane to hit the United States in a decade ventured out to find "widespread devastation," with a downgraded Hurricane Harvey lumbering north in what was "now turning into a deadly inland event."

The first fatality was reported in the hard-hit coastal city of Rockport, where the person died in a house fire during the storm, Aransas County Judge Burt Mills said Saturday afternoon. "We didn't know about it until today," he said.

At least a dozen people were injured, Mills said.

With dire warnings of tornadoes, torrential downpours and days of flooding to come, broad swaths of southeast Texas were littered with uprooted trees, toppled signs, flagpoles that snapped like toothpicks and clusters of bricks peeled like scabs from walls and rooftops.

Additional fatalities were feared in coastal Rockport, where an estimated 5,000 residents had stayed put for the storm that blasted ashore as a Category 4 around 11 p.m. ET Friday between Port Aransas and Port O'Connor, Aransas County Sheriff Bill Mills said.

Callers to the local emergency dispatch line told of walls and roofs collapsing on people across the city, where an official had warned those who opted to stick out the storm to write their Social Security numbers on their arms for body identification.

Shortly after Harvey was downgraded to a tropical storm, with sustained winds of 70 mph, Saturday afternoon, Gov. Greg Abbott told reporters that the state had more than 1,000 workers involved in search and rescue operations.

"There's been widespread devastation," Rockport Mayor Charles Wax told CNN late Saturday morning. He said emergency workers were going house to house to check on residents and assess damage.

"We've already taken a severe blow from the storm, but we're anticipating another one when the flooding comes," he said.

The storm was a Category 1 by late Saturday morning, packing winds of 75 mph as it slowed its trek northward to just 2 mph. Some places even far inland were predicted to get as much as 40 inches of rain through Wednesday.

While the worst of the storm surge had ended by midday Saturday, the coastal flooding threat was due to increase as already-swollen rivers and bayous get pounded with heavy rain, CNN meteorologist Michael Guy said. Sea water pushed onto the shore also won't recede quickly, he said, meaning "this is going to be a long, ongoing flood event."

Abbott said the 210-mile-long corridor between Corpus Christi and Houston was expected to receive as much as 30 more inches of rain on top of the double-digit rainfall figures that had already fallen.

Harvey wielded the "highest potential to kill the most amount of people and cause the most amount of damage," Brock Long, director of the Federal Emergency Management Agency, had warned. He echoed forecasters who predicted Harvey would be leave areas "uninhabitable for weeks or months," echoing language last seen ahead of Hurricane Katrina in 2005.

Here's where we stand:

Latest developments

-- Even after weakening upon landfall, Harvey was still a dangerous storm and "turning into a deadly inland event," the FEMA chief tweeted.

-- Due to stall over Texas, Harvey could maintain tropical storm strength through early Monday, then weaken into a tropical depression, the National Weather Service predicted.

-- Parts of southeastern Texas remained under a flash flood watch through Tuesday evening, the National Weather Service office in Houston said.

-- More than 300,000 customers on the Texas Gulf Coast had no power around 9:30 a.m. ET Saturday, the Electric Reliability Council of Texas said, amid reports of downed power lines and trees.

-- Heavy rain from Harvey's bands also had reached flood-prone Houston, about 150 miles from the point of landfall.

-- A tide gauge in Port Lavaca, Texas, reported a storm surge of 6.4 feet, the National Hurricane Center said early Saturday.

-- Structural and building problems were reported in Rockport, Aransas Pass, and Port Aransas, Texas, said Tom Beal, a meteorologist with National Weather Service office in Corpus Christi.

-- Corpus Christi officials tweeted Saturday afternoon that evacuees could return "but be advised we are under a water boil advisory & limited wastewater usage due to outages at treatment plants."

-- Coast Guard helicopters rescued 15 people aboard three vessels in distress near Port Aransas on Saturday, according to Capt. Tony Hahn, commander of Coast Guard Sector Corpus Christi.

-- President Donald Trump tweeted early Saturday that he's "closely monitoring" Harvey from Camp David, Maryland. Trump, who plans to visit the storm zone next week, has signed a disaster declaration for Texas.

Damage assessments underway

Firefighters who hunkered down in their station in Rockport as Harvey passed over the city of about 10,000 residents recounted a harrowing night.

The wind was "howling," said Roy Laird, assistant chief of the city's volunteer fire department. "We had probably 140-mph winds earlier."

For hours, Karl Hattman and his family listened to "what sounded like a freight train" roar outside their Rockport home. When the fury calmed, they headed out into the darkness to find many trees down, debris blocking their driveway and Hattman's vehicle damaged by flying roof tiles.

Robert Jackson also likened the force of the storm in Rockport to a passing freight train -- one with "square wheels." He didn't sleep all night.

"It was about the most stressful thing I've ever been through," he said, adding, "It's my last one to ride out, I'll tell you that."

Joey Walker, 25, rode out the storm at a house on Galveston Island. The Galveston Island Beach Patrol employee posted video of near-white out conditions overlooking Stewart Beach.

Taking shelter and bracing for rain

As rain bands reached Houston, Mayor Sylvester Turner urged drivers to stay off the roads.

"This is going to be a major rainmaker," he told CNN Saturday. "We anticipate four to five days of this."

"This thing is turning into quite the marathon," Nick Gignac, of Corpus Christi, told CNN around 2 a.m. ET. "You expect these things to be a quicker flash-and-bang than they are. To be honest, the intensity still hasn't let up as the storm came in. Things were a little lighter than they are right now, and you expect it to get intense and let up. And things have not let up at all."

In San Antonio, about 950 people took refuge in shelters, Woody Woodward, a spokesman for the city fire department, told CNN, adding that there was still plenty of space for more people.

Ten critically ill babies in Corpus Christi were taken to a hospital in North Texas ahead of the storm, the Cook Children's Hospital in Fort Worth said in a statement.

"All our babies made it here safely," Dawn Lindley, a registered nurse with Children's Health Transport Team, told CNN. "The majority ... were premature and had ongoing issues. They were easily accommodated to the hospitals here to make sure they had continued care and the storm wasn't going to be a factor in how they recovered from their illnesses."

The-CNN-Wire

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