Power was gradually being restored but hundreds of thousands of households remained without electricity early Thursday across Texas, the oil and gas capital of the United States, with some facing water shortages as a deadly winter cold spell that pummeled the southeastern part of the country headed east.
The National Weather Service (NWS) issued a winter storm warning for a swathe of the country ranging from east Texas to the East Coast state of Maryland.
The NWS said the storm would bring ice, sleet and heavy snow to parts of Texas, Louisiana, Arkansas and Mississippi as it tracks to the northeast, causing power outages, tree damage and making driving hazardous.
Even though the Arctic air mass was beginning to lose its grip on an area of the country not used to such extreme cold, the frigid temperatures would continue, the NWS said.
"Record cold daily maximum and minimum temperatures are likely to transpire in the South Central US through Saturday morning," it said early Thursday.
"The Plains and Mississippi Valley can expect daily temperature anomalies ranging between 20 and 30 degrees below normal."
President Joe Biden was forced to postpone until Friday a visit to the Pfizer Covid-19 vaccine manufacturing site in Kalamazoo, Michigan, while federal government offices in Washington were to be closed Thursday.
More than 30 storm-related deaths have been reported by media in the United States since the cold weather arrived last week, many in traffic accidents.
Hundreds of thousands of residents of the Texas metropolis of Houston were suffering from both power outages and a loss of water pressure.
"Water pressure is very low," Houston Mayor Sylvester Turner tweeted. "Please do not run water to keep pipes from bursting."
Nearly seven million Texans were being advised to boil their water before drinking it or using it for cooking, Toby Baker, who heads the Texas Commission on Environmental Quality said Wednesday, adding that nearly 264,000 people were impacted by non-operational water systems.
David Hernandez, 38, spent the night at a Houston church with other people who have fled their homes.
"My car got stranded and I was trying to sleep in the car but it was just too cold," Hernandez said. "Liquids in my car were actually turning to ice so it was like sleeping in an ice box.
"I had to come here," he said. "There's no choice."
Power companies in Texas have implemented rolling blackouts to avoid grids being overloaded as residents crank up the heat.
ERCOT, which manages the state grid, said on Wednesday it had restored power to around 1.6 million households. "We are working around the clock to restore power to Texans," ERCOT president Bill Magness said in a statement.
According to PowerOutage.US, 674,000 customers in Texas were still without power by Thursday morning, the only one of the US's 48 continental states to have its own independent power grid.
- 'Nearly a failed state' -
Beto O'Rourke, a former Democratic presidential candidate from Texas, told MSNBC television the situation in the Lone Star State was "worse than you are hearing."
"Folks have gone days now without electricity. They're suffering," he said.
"So much of this was avoidable," O'Rourke added.
"The energy capital of North America cannot provide the energy needed to warm and power people's homes in this great state. We are nearing a failed state in Texas."
Austin Energy, the local power company in the capital city of 950,000, said tens of thousands of area customers were without electricity, and that whilst they were able to start restoring power in some spots, it was not expected to stay on indefinitely.
The energy company published the locations of "warming centers" set up in local schools.
As electricity companies struggle to get power restored, Austin-Bergstrom International Airport resumed flights on Wednesday after a two-day hiatus caused by heavy snowfall.
Jeff Zients, the White House Coronavirus Response Coordinator, said the cold weather was impacting delivery and distribution of Covid-19 vaccines.
"There's certain parts of the country, Texas being one of them, where vaccination sites are understandably closed," Zients said.
"What we're encouraging governors and other partners to do is to extend hours once they're able to reopen."
Many weather-related deaths so far have resulted from traffic accidents, but Houston police said a woman and a girl died from carbon monoxide poisoning after sitting in a car in a garage with the engine running to keep warm.
And emergency medical authorities around the state said dozens of others have been treated for suspected carbon monoxide poisoning, while 77 were treated for hypothermia in northern Texas Tuesday.
A dozen animals -- including one 58-year-old female chimpanzee -- died during the freeze at rescue sanctuary Primarily Primates near San Antonio, the organization said on its website.
The winter storm spawned at least four tornadoes, according to Atlanta-based weather.com, including one in North Carolina on Monday that killed at least three people and injured 10.
Across the southern border, Mexican officials said six people died after temperatures plunged.