SAN ANTONIO — A second winter storm swept through the southern United States on Wednesday, another blow to a region where at least 18 people have died and millions remain without power, putting them at risk of hypothermia, with the additional challenges of contaminated water and dwindling food supplies.

More than 100 million people live in areas of the country under some kind of winter weather warning, the National Weather Service said in an advisory Wednesday, with more bad weather to come.

The storm that brought additional snow and ice to Texas and elsewhere in the South spun east across the Mississippi and Tennessee valleys Wednesday and was expected to move through the Mid-Atlantic and New England — with serious icing expected in Louisiana late Wednesday, and more snow forecast in Arkansas and probably central Tennessee, according to The Washington Post’s Capital Weather Gang.

In Texas, more than 3 million customers were still in the dark Wednesday afternoon, according to poweroutage.us, which tracks outages nationwide, along with significant power outages in nine other states. Rolling blackouts continued in several states, including Oklahoma, Arkansas, Louisiana and Mississippi.

Conditions in Texas turned dire, with the water supply disrupted in several cities and officials saying it could be days before power is restored in many parts of the state. Calls intensified for an investigation into what caused the large-scale failure of the state’s power grid, with much finger-pointing but no answers.

Gov. Greg Abbott (R) blamed wind turbines that had frozen in the extreme cold, telling Fox News on Tuesday night that “our wind and solar got shut down.”

But problems with renewable energy sources were only a small part of the problem. Much bigger trouble lurked among thermal power plants that are primarily run on natural gas and that seized up in the cold. Pressed to defend his attacks on renewable energy during a news conference Wednesday afternoon, Abbott declined to repeat them — and acknowledged that frozen wind turbines were not the main cause of the power shortage.

Criticism of the state’s electric grid operator, the Electric Reliability Council of Texas (ERCOT), was loud and bipartisan. ERCOT blamed a combination of factors, including “frozen wind turbines, limited gas supplies, low gas pressure and frozen instrumentation,” for the outages. With demand continuing to surge, power would not be restored, the operator said, until those problems were resolved. It could take weeks.

Abbott also blamed the operator and called for its leaders to resign. The state’s Democratic lawmakers homed in on the fact that five of the council’s 15 board members — including its chair and vice chair — live outside the state.

“Board members should understand the impact of their actions & must be held accountable,” state Sen. Carol Alvarado, a Democrat who represents Houston, said in a tweet.

ERCOT chief executive Bill Magness responded to the torrent of criticism by saying that accountability could wait until “after we get the power back on.”

The operator, which manages the flow of electricity to more than 26 million Texas customers, acknowledged Wednesday that it was struggling mightily to do so. After restoring power to 700,000 homes overnight Tuesday, it ordered local utilities to keep the lights off at 2.8 million more homes Wednesday morning — and warned that worse could come Wednesday night as another cold front pushed through the region.

With the statewide operator ordering power cuts to avoid a total system collapse, local utility companies said they had little control over when service would be restored or rolling blackouts would cease. The blackouts were needed, Austin Energy General Manager Jackie Sargent told local NBC affiliate KXAN, to “ensure a statewide collapse does not occur.”

Millions of Texans are enduring freezing temperatures amid a large-scale failure of the state’s power grid. (Lindsey Sitz, Spike Johnson/The Washington Post)

Austin was hit with an ice storm Wednesday, exacerbating its problems. Sargent said work crews scrambling to fix blown transformers and downed power lines reported that frustrated residents were “threatening them, harassing them, distracting them and even throwing things at them.”

Sargent pleaded with them to stop.

“I know that these are untenable circumstances,” she said. “But, please, I beg of you.”

Officials also began warning of water supply disruptions, signaling a new and dangerous phase of the weather crisis. The water supply was disrupted in Fort Worth, Galveston and Corpus Christi. In San Antonio and Houston, residents were told to boil water.

Austin officials begged residents not to use their washing machines or dishwashers, or run taps or fill bathtubs. At Houston’s William P. Hobby Airport, the water shortage was so severe that airport authorities canceled all flights for the day. Airport officials were forced to manually bring in “nonconsumable water” just to flush airport toilets.

White House press secretary Jen Psaki said at a briefing Wednesday that the Federal Emergency Management Agency was supplying emergency generators to Texas and was prepared to send diesel.

“FEMA is also supplying Texas with water and blankets at their request,” Psaki said. “We are preparing to quickly process requests from other states for emergency assistance.”

President Biden approved an emergency declaration for Texas over the weekend, and he spoke by phone Tuesday night with the governors of Texas, Louisiana, Kentucky, Kansas, Tennessee, Mississippi and Oklahoma, she said.

In Houston, the state’s largest city, public safety officials warned about the dangers of carbon monoxide poisoning after emergency calls related to people using charcoal grills to try to heat their homes. “SPREAD THE WORD: The number of people being admitted to local hospitals for carbon monoxide is rising at a disturbing rate. Do not bring any outdoor appliances (grills, etc) inside, or run your car inside the garage,” Harris County Judge Lina Hidalgo tweeted.

Hidalgo said the county had received reports of at least 50 cases of carbon monoxide poisoning, calling it the second-biggest challenge the county is facing after the widespread power outages, a situation she described as “a nightmare.”

State Rep. Jon Rosenthal, whose Houston home was without power for 40 hours before electricity returned and he found it flooded from burst pipes, said he has been receiving nonstop calls from constituents.

“I am very angry. This is unforgivable,” said Rosenthal, who represents northwest Houston.

“It’s a massive failure of Texas power, not just the grid, but the whole system,” said Rosenthal, a mechanical engineer who has worked in the oil and gas industry for 25 years.

For decades, Texas has evaded federal regulation of its power generation industry — a system in which the state pays only for the energy generated, but offers no incentives to companies to build reserves for times of extreme demand. Lawmakers such as Republican Rep. Lyle Larson have long warned that the state’s rejection of a “capacity market” — creating a structure for companies to store energy in reserve — would set up Texans for failure.

It happened in 2011. After a similar February cold snap plunged temperatures below freezing for four consecutive days, generators were unable to meet demand and more than 1 million South Texas customers lost power at its peak. Rolling blackouts affected more than 3 million statewide. The federal government noted deficiencies across energy sources in a report and, specifically, recommended more adequate winterization procedures for the infrastructure.

Lawmakers said few of those recommendations were adopted. The state’s public utility commission a decade ago rejected that model, in part because it would increase costs for businesses and consumers attracted to Texas’s affordable power rates and low cost of living, Larson said. The following summer, it happened again on the other extreme of the thermometer.

Texas House Speaker Dade Phelan (R) on Tuesday called for a joint hearing of two House committees to review the causes of the crisis, and Abbott said reform legislation is a priority. But Democrats and some Republicans say they have heard it all before. State leadership has had decades of chances to fix the problem for future Texans but has lacked the consensus or will to create substantive change, they said.

“There are lot of folks culpable for this and there is going to be a reckoning of the policy decisions that have been made in the past,” said Larson, who represents a district that includes San Antonio.

The forensics of Texas’s winter catastrophe also reveal a “woeful lack of preparation,” within the state’s deregulated ecosystem, Rosenthal said. Texas is not alone in having made few investments in the overall infrastructure of its public utilities and state entities failing to respond to the realities of climate change.

“Maximizing profits means you don’t fix stuff unless it’s actually broken,” he said. “We lack a focal point for accountability, so we are not regulating at the level that would require companies to do things like winterize their stuff.”

Meanwhile, residents like Juan Hernandez just want heat and water.

The Houston oil field worker, his wife and son ended up at a shelter run by a local mattress store owner. Jim “Mattress Mack” McIngvale opens up his sprawling Gallery Furniture store to residents anytime there is civic crisis.

“We’re out of power and out of water,” Hernandez said. “Our house is cold, you can see smoke come out of your mouth. I’m disappointed in the light company because they weren’t prepared and they knew this was coming. We shouldn’t be suffering this. I can understand pipes freezing, but no power shouldn’t be happening.”

Keith and Cheryl Lynch also took refuge at Gallery Furniture after several days without power.

“We have no power, no water, no nothing,” Cheryl Lynch said. “We didn’t have . . . food to eat. This is really something else. But I’m not angry, it’s just God’s work.”

In coastal Galveston, more than 90 percent of homes in the city lost power, and most of them have been without it for more than 36 hours, city manager Brian Maxwell said. The temperature inside most homes was at freezing or below.

“It’s hard to believe saying it’ll be 38 degrees tonight is a good thing. That’s downright toasty compared to 18 this morning,” Maxwell said.

“We’ll recover. We’re no strangers to having disasters here on the island, so we’ll overcome it. But it does shake your trust in what’s a given,” he said.

Christian Smith moved to Galveston with his family in November and started his own home-repair business on the island. Smith, his wife and their three daughters have been largely without power since 1:30 a.m. Monday. The temperature inside dropped into the 30s, and glasses of water sitting out on the counter began to freeze.

Though Smith, 27, isn’t a licensed plumber, he is trained to do emergency repairs. When it became apparent that pipes at homes across the island were frozen and bursting, Smith posted on local Facebook groups to offer his help.

“I’m just helping out where I can,” Smith said Wednesday as he drove nearly two hours north to Conroe to pick up a part to repair a water heater.

Smith worked for 15 hours on Tuesday, finally returning home around 2 a.m. when he ran out of materials. He was at Home Depot when it opened Wednesday morning but said supplies were limited.

“I don’t know many people that don’t have some sort of damage to their house right now,” Smith said.

Going on day three of the storm, San Antonio coffee shop owner Tatu Herrera, 41, said being a Texan right now isn’t so great.

“That’s Texas. We want to be so independent, we want to do all these things on our own, and we can’t even do it correctly. I think at the end it’s greed,” Herrera said. “Everyone is looking at Texas, saying, ‘What’s going on?’ Texas is supposed to be tough, that’s the vision you have of Texas. And then one snowstorm and we’re out of everything.”

Herrera had been without power and water for two days until Wednesday morning. He and his wife transported nearly 30 people to the warming center on Tuesday who were without power and couldn’t make the journey themselves. He said it’s been mostly up to community members to help one another.

“We’re upset with the fact that all this is happening and there’s no help. You call [the water utility company], they don’t have an answer. Think of all those senior citizens that require electricity and don’t have that help. What’s going to happen to them?

“We’ve got to figure out why everything failed, we’ve got to figure out who is responsible and how to prevent this from happening again,” he said. “This is going to happen again eventually, and when it does, we should be ready.”

Silvia Foster-Frau, Brittney Martin, Paulina Villega, Tim Craig, Matthew Cappucci, Paulina Firozi and Felicia Sonmez contributed to this report.