CORPUS CHRISTI, Tex. — Residents of the Gulf Coast hunkered down late Friday amid dire warnings of a major natural disaster as Hurricane Harvey, having intensified into a Category 4 storm with 130 mph winds for a few hours, roared ashore just to the northeast of this South Texas city.

The National Hurricane Center reported at 10 p.m. CDT that the center of the eye of the cyclone had just crossed the Texas shoreline over the northern end of a barrier island about four miles east of the city of Rockport. Initial reports compiled by the National Weather Service said numerous structures in Rockport had been “destroyed” and described “buildings collapsed with people trapped inside.” But those early reports, distributed on social media, remained sketchy as the storm raged into the middle of the night.

Rockport city manager Kevin Carruth said multiple people were taken to the county’s jail for assessment and treatment after the roof of a senior housing complex collapsed, according to the Associated Press. Carruth also said that Rockport’s historic downtown area has seen extensive damage, AP reported.

About 10 people in Rockport have been treated for injuries suffered during the hurricane, KIII-TV reported. Earlier Friday, Rockport Mayor Pro Tem Patrick Rios told the TV station that hose who chose to stay put “should make some type of preparation to mark their arm with a Sharpie pen,” implying doing so would make it easier for rescuers to identify them.

Here in Corpus Christi, a city of 320,000 people, lights flickered downtown, where many locals, out-of-town journalists and storm chasers had taken refuge in hotels. Local media reported roofs blown off homes.

Although Harvey made landfall as a Category 4 hurricane late Friday, the National Weather Service downgraded it to Category 3 early Saturday, with maximum wind speed dipping slightly to 125 mph, when it made a second landfall at Copano Bay, a few miles from Rockport.

The most intense winds appeared to stay just offshore as the hurricane crept northward, likely driving the worst of the storm surge flooding into the central Texas coast. City officials cautioned that the hurricane was expected to pound the city until well past midnight.

Harvey is easily the strongest hurricane to hit the United States since Charley in 2004 and the first Category 3 or greater storm (winds of 111 mph or higher) since Wilma in 2005. Forecasters and government officials, scrambling to deal with a storm that popped up this week after being a mere tropical depression in the western Gulf of Mexico, warned of catastrophic flooding, ferocious winds and a storm surge that could reach 12 feet.

Soon after the outer bands of Harvey reached the South Texas coast, Gov. Greg Abbott (R) on Friday afternoon urged citizens to evacuate low-lying and coastal areas immediately. President Trump said Friday night that he has signed a disaster proclamation in Texas after Abbott sent him a written request.

“The storm surge, coupled with the deluge of rain, could easily lead to billions of dollars of property damage and almost certainly loss of life,” Abbott wrote. “It is not hyperbole to say that if the forecast verifies, Texas is about to experience one of the worst natural disasters in the history of the state.”

White House aides said that Trump would visit Texas next week.

Harvey is the first natural disaster faced by the Trump administration. Trump on Friday tweeted that he had spoken with the governors of Texas and Louisiana and was “here to assist as needed.”

Sen. Charles E. Grassley ­(R-Iowa) gave the president a warning via Twitter: “keep on top of hurricane Harvey dont mke same mistake Pres Bush made w Katrina.”

Here in Corpus Christi, city and county officials said they are ready for the worst.

“Game on,” said Mayor Joe McComb at a news conference. “We’re looking forward to having a very good positive result from this storm. We’ll get through this; we’ll be better for it because the community has been pulling together.”

But many residents were nervous as the storm approached Friday.

In nearby Aransas Pass, 66-year-old Mike Taylor said he was resigned to riding out the storm in his one-story house just a few blocks from the water. As part of routine hurricane preparations, the town maintains a list of residents who need help in leaving. Taylor, who does not own a car and lives with his disabled 40-year-old son, said he thought he was on the list.

No one came for him.

“Now, I am just out trying to find some groceries,” said Taylor, who was trudging along Route 35 in a yellow raincoat, even though all the grocery and convenience stores appeared closed. “I lost my driver’s license because I am nearly blind.”

Several hundred miles of the Texas Gulf Coast are under hurricane and storm-surge warnings. Harvey is expected to stall over the coast and could even drift back out over open water, drawing fresh energy from the warm gulf waters before meandering ashore again closer to Galveston.

That scenario would deliver historic amounts of rain to the region, with some models showing accumulations in feet rather than inches. Flooding is likely in and around Houston.

“Small streams, creeks, canals, and ditches may become raging rivers. Flood control systems and barriers may become stressed,” the National Weather Service said in an advisory Friday.

Thousands of people were reportedly stuck on cruise ships in the gulf and unable to enter the closed Port of Galveston as the winds picked up.

Jennifer Cantrell, 37, a Houston social worker who endured Hurricane Ike in 2008, bought four 40-pound bags of topsoil to place at the foot of her door in her first-floor apartment.

“We got to worry about all the folks who moved here in the last years and haven’t seen a hurricane yet,” she said outside a Citgo gas station, where she had stopped to stock up on cigarettes. “You’ve just got to be prepared to be indoors for days with no electricity, no water.”

The Texas Military Department deployed about 700 members of the State Guard and National Guard around the coastal region on Friday as the storm moved in. Black Hawk and Lakota helicopter crews were put on standby for search and rescue.

The American Red Cross mobilized staffers from across the country. Paul I. Carden Jr., regional disaster officer for the Red Cross’s National Capital Region in Washington, said in Corpus Christi that residents are foolish if they decide not to evacuate.

After the storm, the Red Cross will be providing cleanup kits, health and mental-health professionals, and spiritual-care workers to help residents cope, he said.

“This is going to try a person’s faith,” Carden said.

A steady and orderly stream of traffic flowed out of Corpus Christi, heading for higher ground. But many thousands decided to ride out the storm.

Friday morning, residents Phyllis Sweeney and Gary Balding told their story of fleeing the wrath of tropical storms. They live on a 41-foot sailboat, having moved to Corpus Christi from Key West. Two weeks ago, they tried to sail to the Yucatan Peninsula in Mexico but were battered by Hurricane Franklin.

“We got within 20 miles, and couldn’t get there because the winds and currents were blowing in the wrong direction,” said Balding, 68. “We thought, ‘Okay, we’ll go to Corpus Christi, and everything will be cool.’ ”

Now they’re in the path of Harvey. They fled the boat early Friday and checked into the Holiday Inn downtown. The hotel has become a refuge for stranded tourists, boaters, storm chasers and journalists. But Sweeney, 70, is worried about the hotel, which is surrounded by skyscrapers.

In the ranching town of Kingsville, about 40 miles southwest of Corpus Christi, Nick Harrel III, 65, who runs Harrel’s Pharmacy and Soda Fountain, said he has weathered many hurricanes and is going to ride this one out.

“After the initial fear, you just take a deep breath and do what you can to prepare,” he said. “I have storm shutters that fit my windows, and I bought a generator last year. I am coming late to being a Boy Scout.”

Silver Marquez, 34, went from table to table at the crowded El Tapatio taqueria in Kingsville, selling pan de campo, a flatbread traditionally cooked in Dutch ovens at cattle camps in South Texas.

“I have plain, bacon and cheese and jalapeño,” said Marquez, a Kingsville native. “They are fresh and hot, and I am selling a lot of them because people are stocking up for the hurricane.”

Santos Rojas, 72, said he isn’t preparing for the hurricane much beyond buying bottled water and pan de campo.

At the small rural shrine to Don Pedrito Jaramillo, a revered Mexican American folk saint who died in 1907, believers filed in to ask for protection from the storm. Jaramillo, a native of Guadalajara, Mexico, had a reputation for healing in a time and place where few people had access to conventional medical care.

Aurora Zapata, 42, a homemaker, and her daughter, Dina Zapata, 12, both of Falfurrias, were lighting candles at the shrine Friday afternoon as the first bands of rain began to make landfall.

“We are just praying to Don Pedrito to protect us, our whole family and our town from this hurricane,” Aurora Zapata said.

Her daughter agreed. “There is nothing we can do to fight the storm, but we all know that God and the Virgin and Don Pedrito are always there for us.”