An unusually harsh winter storm in Texas has killed at least one person and left millions of customers without power in the state amid dangerously low temperatures.
A spokesman for the Harry County Sheriff's Department told reporters Monday afternoon that a homeless man living in a van had been found dead from suspected exposure to the cold.
Meanwhile, fire officials in Harris County said they were responding to a home in Houston where six people -- including 4 children -- who had suffered from carbon monoxide poisoning. Officials said the family had been burning a fire for warmth for about four hours.
Texas Gov. Greg Abbott said Saturday that Texas "is facing a very dangerous winter storm" over the coming days that will "make movement virtually impossible."
He called the storm "unprecedented" in the state's history.
Temperatures in north Texas remained below zero as of Monday morning, with Amarillo reporting a temperature of minus seven degrees, according to WeatherWX.com. Dallas had reached 10 degrees by mid-morning, with Houston at 20 degrees.
Rotating power outages were initiated by the Electric Reliability Council of Texas, or ERCOT, early Monday morning, meaning thousands went without electricity for periods of time as temperatures fell into the teens near Dallas and 20s (about minus 5 degrees Celsius) around Houston.
Austin's electric utility Austin Energy told residents the outages may be longer than usual, prompting angry social media replies from Texans who said they'd been without power for five or more hours.
"Typical events allow short durations of each outage, but outages are longer if the ERCOT grid requires -- which is what we're seeing in today's event," Austin Energy wrote on Twitter.
The utility advised residents to keep their keep their thermostat set to 68 degrees or lower, and to avoid using their oven or washing machine. Businesses were likewise advised to minimize operations to conserve energy.
Some turned to social media to vent their frustration with the outages.
"My parents, who are elderly, have been without power since 2am," one user wrote. "They are over 70years old. How can I get them some power?!"
"This is downright dangerous," wrote another user. "No power for 5+ hours and sub zero windchills."
Kent and Brazos counties, on opposite sides of the state, were hardest hit with nearly all customers losing power early Monday morning, according to an online power outage tracker.
"The electricity grid continues to lose generation," Houston Mayor Sylvester Turner told residents on Twitter. "If you are without power, you may be without power throughout the day. Please do your best to stay warm safely. Check on our seniors."
Temperatures are expected to plunge again Monday night, and more snow and wintry precipitation is forecast to fall Tuesday night into Wednesday morning.
President Biden also declared an emergency in Texas in a statement Sunday night. The declaration is intended to add federal aid to state and local response efforts.
The storm has also snarled travel. Austin-Bergstrom International Airport in Austin canceled all flights on Monday, while Dallas-Fort Worth Airport said all inbound flights would be held at their origins until 11 a.m. CT on Monday "due to snow and ice."
More than 760 flights were canceled at Dallas-Fort Worth International Airport, and at Dallas Love Field most of the nearly 200 flights for Southwest Airlines, the airport’s main carrier, were canceled on Sunday.
American Airlines said about 345 of its flights were canceled at DFW Airport, its hub, by early Sunday afternoon. The airline said the storm was also affecting its flights across the region, with operations reduced and canceled at airports across Texas, Oklahoma and Arkansas.
The current storm system formed Friday night, stretching across much of the Ohio Valley and Appalachians into the Northeast. Texas issued a winter storm warning for the entire weekend and the early part of the week.
"Maximum cold weather preparations MUST be completed today," Jeff Lindner, a Harris County Flood Control District meteorologist, tweeted Sunday morning. "Time is running out and conditions will quickly deteriorate late this afternoon and evening."
The storm dropped heavy snow across Oklahoma, creating dangerous driving conditions. Several people were hospitalized after a fiery crash involving multiple semi-trucks and passenger vehicles on a highway near Oklahoma City, according to Fox 25's Connor Hansen.
"Do not get out if you don't have to," the Oklahoma Highway Patrol warned Sunday.
Road safety will be a top priority after Fort Worth saw a pileup last week involving over 130 vehicles, including 18-wheelers and passenger cars, which resulted in six deaths and dozens of injuries.
In El Paso, a 15-car pileup on Sunday morning served as a warning to anyone wanting to travel, but fortunately no deaths were reported as of Sunday, KFOX14 reported.
Fox News' Peter Aitken and the Associated Press contributed to this report.