Hurricane Harvey lashed central Texas with torrential rains on Saturday, raising fears of "catastrophic" flooding after the megastorm -- the most powerful to hit the United States since 2005 -- left a deadly trail of devastation along the Gulf Coast.
The latest forecasts show that Harvey, now downgraded to tropical storm status, will hover along the shore for the next four or five days -- a dangerous possibility given the amount of potential additional rainfall.
The storm flattened buildings, toppled mobile homes, sent boats floating into deserted streets and left hundreds of thousands of people without power on the Gulf Coast, home to some of the country's most important oil refineries.
While only one person was known to have died, officials said they feared the worst was yet to come, with large areas of Texas under flash flood warnings and sporadic tornadoes touching down, tearing roofs off houses.
Harvey made landfall late Friday as a Category Four hurricane, pummeling the small town of Rockport outside Corpus Christi with sustained winds of 130 miles (215 kilometers) per hour, the National Hurricane Center (NHC) said.
It then made a second landfall a few hours later just north of Rockport, which was one of the hardest-hit areas.
While most residents did heed advice to head to safety, some hunkered down in Corpus Christi -- a city of about 325,000, where residents have been told to boil their water before using.
"I've never seen anything like this. We do have strong winds -- we're right next to the bay -- but nothing like last night," store owner Brandon Gonzalez told AFP.
"I mean, I was even a little bit terrified of what was going to happen. Our building was just shaking back and forth. It really got bad. I think we held up pretty good though."
'Long and frustrating'
Texas Governor Greg Abbott said at least 20 inches (50 centimeters) of rain had fallen in some areas -- with another 20 or 30 inches possible.
"Our primary concerns remains dramatic flooding," Abbott told reporters.
As of late Saturday, about 230,000 customers were still without power, providers said. Roads were difficult to navigate due to debris and downed power lines.
"Rainfall of this magnitude will cause catastrophic and life-threatening flooding," the NHC warned.
The Federal Emergency Management Agency said there should be no illusions about the long-term impact.
"This is going to be an unprecedented long and frustrating event for the state of Texas," FEMA director Brock Long told MSNBC. "The recovery from this disaster is going to be years."
Emergency services were struggling to make headway as rains continued to pour down, although the Coast Guard managed to airlift 20 people and a dog to safety.
One person was confirmed to have died, with officials in Aransas county saying the victim had perished in a fire that broke out in his house.
President Donald Trump, aware of the damage to George W. Bush presidency's for his tardy response to Hurricane Katrina, said he was closely monitoring relief efforts from Camp David in Maryland.
"We are leaving nothing to chance. City, State and Federal Govs. working great together!" he tweeted, after meeting with his cabinet via teleconference to discuss the ongoing emergency operation.
The storm represents the first major domestic challenge for Trump, and he plans to head to Texas next week.
In Rockport, a local school and airport were among the places to suffer major damage while homes were also burnt to the ground as power cables caught fire. There were similar scenes in nearby Corpus Christi.
Brian McNoldy, a hurricane expert at the University of Miami, said a strong ridge of high pressure was preventing the storm from dispersing.
"There's no sign of it really moving in a foreseeable future," he told AFP.
Coastal Texas is a fast-growing area, with some 1.5 million people moving into the region since 1999. It is also home to a large number of oil refineries and a number of major ports.
US authorities said about 22 percent of crude production in the Gulf of Mexico, accounting for more than 375,000 barrels a day, was shut down as of Friday.
"We recognize that the ports in this region are critical and vital to the nation's economy," said Captain Kevin Oditt, incident commander for the Coast Guard's Houston-Galveston post.
"We are preparing to open ports once the storm has passed or weather conditions permit."
Many residents who fled the worst-affected areas in Texas headed for the city of San Antonio, where temporary shelters are run by the fire department.
"I only got what you see me with. Everything I had, I had to leave. Everything," Michael Allen, an evacuee from Corpus Christi, told AFP.
Harvey is the most powerful hurricane to hit the mainland since Wilma struck Florida 12 years ago.
2005 was a huge year for hurricanes -- before Wilma, Hurricane Katrina pummeled New Orleans, leaving more than 1,800 dead.
In the Texas town of Victoria, Mayor Paul Polasek told CNN the storm was "not as bad as it could have been," but he nevertheless put in place a dusk-to-dawn curfew.
"Stay calm and relaxed," Polasek advised residents. "Do not travel. Restrict travel. It's not safe. (...) And help your neighbors."