HOUSTON — What felt like an apocalyptic onslaught of pounding rains and rapidly rising floodwaters brought the nation’s fourth-largest -city to its knees Sunday, as highways and residential streets turned to rivers, waist-high waters choked off access to homes and hospitals and officials begged boat owners to pitch in with a massive and frantic rescue operation.
It was a scene that evoked Hurricane Katrina in Louisiana in 2005, with worried residents punching holes in roofs in anticipation of the water rising even higher and people being rescued by helicopters from soggy rooftops.
The chaos inflicted by the remains of Hurricane Harvey played out across an enormous swath of Texas and most conspicuously in this metropolitan area of 6.6 million that has long been used to major storms blowing in off the Gulf of Mexico, but has seldom, if ever, faced a scene quite like this one.
The storm, which made landfall late Friday as a Category 4 hurricane, so far has left five people reported dead, many others injured and untold numbers of homes and businesses flooded, damaged or destroyed on both the coast and far further inland. Even the National Weather Service seemed overwhelmed by the scope of the devastation.
“This event is unprecedented & all impacts are unknown & beyond anything experienced,” the federal service said on Twitter Sunday. “Follow orders from officials to ensure safety.”
Some people posted addresses of their flooded homes on Twitter and Facebook, with photographs of half-submerged furniture or families stranded on roofs, to try to draw the attention of rescue crews.
Mr. Turner announced the opening of the George R. Brown Convention Center as a shelter, and said the number of other shelters to open would “dramatically increase.” West of Houston, San Antonio was housing roughly 1,000 evacuees in emergency shelters as of Sunday afternoon. A few hundred evacuees are also in emergency shelters in Dallas, to the north, and that city was preparing to house up to 5,000 more in a “mega-shelter” planned to open as early as Tuesday morning in the Kay Bailey Hutchison Convention Center.
In Houston, harrowing close calls shook many families.
Maya Wadler, 17, recalled the moments before she was rescued from her home Sunday around 4 a.m. The water, she said, “bubbled up from the doors, seeped in from the windows.”
“Everywhere you turned,” she said, “there would just be a new flowing puddle. It just kept filling. It passed the outlets. I was so scared. We didn’t know what would happen. And there is no one you can call.”
Ms. Wadler was eventually helped onto a dump truck driven by rescue workers.
“I was sitting in the corner holding my dad really tight,” she said. “I usually just trust my parents that everything is going to be O.K. But I looked up and I saw that my dad was closing his eyes, the water was getting in his eyes. And I just thought: He has absolutely no idea where we are going to go.”
For a vast swath of southeast Texas, there may be still more trouble in the days ahead. The National Weather Service said the storm was expected to linger for a number of days. It predicted an additional 15 to 25 inches of rainfall along the upper Texas coast and southwest Louisiana through Friday. The service also raised the possibility of 50 inches of total rainfall in some areas, exceeding previous Texas rainfall records.
Flooding was reported in numerous communities in the Texas interior between Houston, to the east, and Austin and San Antonio, to the west. On Sunday, a mandatory evacuation order was issued for the city of La Grange, where the National Service’s projected that the Colorado River would crest at 49.1 feet, according to the city’s website.
As inland communities struggled with the flooding crisis, coastal communities that took the brunt of the hurricane’s pounding remained punch-drunk.
In Rockport, where the storm made landfall, hundreds of homes, apartments, businesses churches and government offices were damaged or destroyed. On Sunday morning, parts of the city were a wreck, pervaded by the sweet stench of gas, wind-battered and littered with downed power lines and tilting utility poles. Injured dogs wandered the streets.
The storm also blew through key areas for the United States oil and gas industry and was already causing some disruption of production. Exxon Mobil, for instance, said on its website Sunday that it was shutting down operations at its huge Baytown refining and petrochemical complex because of flooding, while heavy rain prompted Royal Dutch Shell to close a large refining facility at Deer Park.
Shell, one of the largest producers in the Gulf of Mexico, said it had closed two offshore production platforms, Perdido and Enchilada Salsa, and evacuated most of the workers.
Still, the gulf produces substantial quantities of oil and gas, and analysts say it is likely that the impact on energy prices and supplies will be limited by the substantial stocks of oil available, and products like gasoline that are on hand because of a long period of booming global output.
In the long term, Texas is likely to face a massive, multibillion-dollar rebuilding effort that may affect a generation — and what is sure to be daunting and sometimes depressing era of government trailers, red tape and fights with bureaucrats and insurance companies.
The federal government is promising a muscular response, with 5,000 federal employees — including members of the Coast Guard, the Environmental Protection Agency and the Agriculture Department — on site in Texas and Louisiana to assist state and local officials.