(CNN) -- A devastating winter storm has crippled the power grid in Texas and caused nearly 3.4 million outages as of Wednesday morning, leaving much of the state in the cold and dark for several days.
The lack of power to about a quarter of the state has created a widespread emergency, with families huddling in homes or cars without heat, burst water pipes, failing water systems and gasoline shortages.
Barbara Martinez said she had been burning firewood to try to heat her suburban Houston home, which had been without power from early Sunday until Tuesday.
"We got power for four hours and then it went off again and it stayed off for a few hours, came back for like two hours then went away," she said Wednesday morning. "It's currently off."
The outages cover the areas served by Electric Reliability Council of Texas, or ERCOT, from the counties bordering Mexico up to those touching Oklahoma, and from Houston in the east to rural Big Bend in the west. Yet areas outside of ERCOT's coverage zone, including the eastern border with Louisiana, the northwest panhandle and El Paso in the west, are basically unaffected.
Texas officials are turning on the power company and calling for investigations. But ERCOT's CEO Bill Magness said the company's controlled outages, which down power to millions of customers, had in fact averted the system's total collapse.
"I think from the perspective of the grid collapsing, I think what has happened here is a response that kept the grid from collapsing, that kept us from going into a blackout condition," he said. "Now the difficulties that this has imposed on the citizens of Texas, everybody in the state, have been enormous."
The power issues are likely to continue, especially given that the cold temperatures will last for another day or two. Over 21 million people, or nearly 70% of Texas's population, is currently under some sort of winter weather alert.
ERCOT said Wednesday some power generation is slowly returning and they "hope to reduce outages over the course of the day."
Harris County Judge Lina Hidalgo told NBC on Wednesday she expected the issues to last beyond the severe weather.
"Today is going to get a little warmer ... but those power issues, I expect will continue, and that's what I am telling my community," she said. "This agency is saying things are getting better, but they've been saying that for three days. So, right now, I just want to set expectations."
Why the system is failing
The widespread outages stem from a weather disaster coupled with an unprepared infrastructure.
A winter weather system brought unusually frigid temperatures to much of the central US over the past few days, including in Texas, the country's energy leader. The deep freeze caused demand for power and heating to skyrocket even as it knocked out the state's natural gas, coal, wind and nuclear facilities, which were not ready to function in such cold weather.
The lack of winter preparedness has long been an issue for ERCOT's power system. 10 years ago, a bitter cold snap caused over 3.2 million ERCOT customers to lose power during Super Bowl week. A 350-page federal report on the outages (PDF) found that the power generators' winterization procedures were "either inadequate or were not adequately followed."
Compounding the issue is that Texas's electric system of ERCOT is isolated from the rest of the country, partly as a way to avoid federal regulation. So it cannot simply import power from elsewhere to make up for the shortage.
"When it comes to electricity, what happens in Texas stays in Texas," said Dan Cohan, associate professor of environmental engineering at Rice University. "That has really come back to bite us."
And with temperatures not expected to rise above freezing until Friday, officials worry about how residents will cope without utilities. "I share the frustration of every Texan regarding the loss of power during this winter storm. Millions of people without power during this arctic blast is life-threatening and unacceptable," Lt. Gov. Dan Patrick said.
When asked if leadership of ERCOT should resign, Gov. Greg Abbott said the company had failed.
"They showed that they were not reliable," Abbott said. "These are experts. These are engineers in the power industry. Government has to rely upon on these specialists to be able to deliver in these types of situations."
Weathering the storm without power, heat or water
Meanwhile, many Texans are pinning their hopes of staying warm on backup generators and warming centers.
Some people have turned to unconventional heat sources such as stoves, grills or gas generators -- which raises the risk of carbon monoxide poisoning.
In Harris County, 14 residents have been taken to the hospital with carbon monoxide poisoning and seven of those were children, according to a tweet from the Cy-Fair Fire Department.
Houston officials said Tuesday a woman and girl died from carbon monoxide poisoning after trying to stay warm using a car in a garage.
The Houston Fire Department had responded to 56 fire calls and over 90 calls for carbon monoxide poisoning, Chief Samuel Peña said in a news conference.
"It is critical that you understand the dangers of using open flames inside your homes to try to heat up your homes," Peña said.
The loss of power and failure of backup generators also cut availability of water.
"First, because of the generators that are out, there is now low water pressure and some pipes have burst as well due to the weather," Judge Hidalgo said. "So our hospitals, our firefighters are facing low water pressure, and it's an enormous problem for them."
San Antonio Fire Department confirmed to CNN that the power outages and cold weather were affecting their ability to put out fires. Fire Department spokesperson Joseph Arrington said that firefighters had to change tactics when responding to a fire at an apartment complex early Wednesday.
"Our normal attack would involve multiple hoses and lots of water on the fire, so we've obviously just had to adjust," he said.
Fort Worth Mayor Betsy Price told CNN on Tuesday evening she had been without power or water for around 38 hours.
"If people have neighbors that they know don't have heat and maybe they do, (then) offer to take them in. Let's watch out for each other. Let's try to do the right thing by helping, share what we have," the mayor said.
Galveston said most residents had low or no water pressure due to water line breaks and failures, and the city's water supply is "critically low."
Houston said early Wednesday it is struggling to supply water.
"The City is working very hard to maintain water pressure but it is becoming increasingly difficult. There are 2 requests: please do not run water to prevent pipes from freezing and turn off water if pipes have burst," Houston Mayor Sylvester Turner said in a tweet Tuesday.
CNN's Keith Allen, Dave Alsup, Alisha Ebrahimji, Matt Egan, Carma Hassan, Dave Hennen, Gregory Lemos, Allison Morrow, Paul P. Murphy, Jessica Myers, Andy Rose and Joe Sutton contributed to this report.