OCEAN ISLE BEACH, N.C. — A winter storm that left millions without power in record-breaking cold weather claimed more lives Tuesday, including three people found dead after a tornado hit a seaside town in North Carolina and four family members who perished in a Houston-area house fire while using a fireplace to stay warm.
The storm that overwhelmed power grids and immobilized the Southern Plains carried heavy snow and freezing rain into New England and the Deep South and left behind painfully low temperatures. Wind-chill warnings extended from Canada into Mexico.
At least 11 deaths were reported from other causes, including car crashes and carbon monoxide poisoning. President Joe Biden's administration said the weather was likely to cause delays in shipments and deliveries of the COVID-19 vaccine.
North Carolina's Brunswick County had little notice of the dangerous weather, and a tornado warning was not issued until the storm was already on the ground.
The National Weather Service was "very surprised how rapidly this storm intensified ... and at the time of night when most people are at home and in bed, it creates a very dangerous situation," Emergency Services Director Ed Conrow said.
In Chicago, a foot and a half (46 centimeters) of new snow forced public schools to cancel in-person classes for Tuesday. Hours earlier, along the normally balmy Gulf of Mexico, cross-country skiier Sam Fagg hit fresh powder on the beach in Galveston, Texas.
The worst U.S. power outages were in Texas, affecting more than 4 million homes and businesses. More than 250,000 people also lost power across parts of Appalachia, and another quarter million were without electricity following an ice storm in northwest Oregon, according to poweroutage.us, which tracks utility outage reports. Four million people lost power in Mexico.
Texas officials requested 60 generators from the Federal Emergency Management Agency and planned to prioritize hospitals and nursing homes. The state opened 35 shelters to more than 1,000 occupants, the agency said.
More than 500 people sought comfort at one shelter in Houston. Mayor Sylvester Turner said other warming centers had to be shut down because they lost power.
Utilities from Minnesota to Texas implemented rolling blackouts to ease the burden on power grids straining to meet the extreme demand for heat and electricity.
Blackouts of more than an hour began around dawn Tuesday for Oklahoma City and more than a dozen other communities, stopping electric-powered space heaters, furnaces and lights just as temperatures hovered around minus 8 degrees.
Oklahoma Gas & Electric rescinded plans for further blackouts but urged users to set thermostats at 68 degrees, avoid using major electric appliances and turn off lights or appliances they are not using.
Nebraska's blackouts came amid some of the coldest weather on record: In Omaha, the temperature bottomed out at 23 degrees below zero overnight, the coldest in 25 years.
The Southwest Power Pool, a group of utilities covering 14 states, said the blackouts were "a last resort to preserve the reliability of the electric system as a whole."
The outages forced a Texas county to scramble to administer more than 8,000 doses of Moderna's coronavirus vaccine after a public health facility lost power early Monday and its backup generator also failed, said Rafael Lemaitre, a spokesman for Harris County Judge Lina Hidalgo.
County officials distributed the doses at three hospitals, Rice University and the county jail because those places had large groups of people available where they would not have to drive and with appropriate medical personnel on hand.
"It feels amazing. I'm very grateful," said Harry Golen, a college sophomore who waited for nearly four hours with his friends, much of it in the cold. He was among the last people to get the shots, which otherwise would not have reached students until March or April.
Texas officials said more than 400,000 additional doses due now will not arrive until at least Wednesday because of the storm.
In North Carolina, the weather service's office in Wilmington dispatched a team to confirm that a tornado did indeed touch down and to survey damage in Brunswick County, said Mark Willis, the office's meteorologist in charge.
Three people died and 10 were injured when the apparent tornado tore through a golf course community and another rural area just before midnight Monday, destroying dozens of homes.
Sharon Benson, 63, said her roof was damaged and her garage door blown off. Windows were shattered and nearby trees were uprooted.
"The sky lit up and there was a lot of pop-pop-popping" and thunder, she said.
Authorities in multiple states reported deaths in crashes on icy roads , including two people whose vehicle slid off a road and overturned in a waterway in Kentucky on Sunday, state police said.
In Texas, three young children and their grandmother died in the Houston-area fire, which likely began while they were using a fireplace to keep warm during a power outage, a fire official said.
Other Texas deaths included a woman and a girl who died from suspected carbon monoxide poisoning in Houston at a home without electricity from a car left running in an attached garage, and two men found along Houston-area roadways who likely died in subfreezing temperatures, law enforcement officials said.
In west Tennessee, a 10-year-old boy died after falling into an ice-covered pond on Sunday during a winter storm, fire officials said.
Several cities had record lows: In Minnesota, the Hibbing/Chisholm weather station registered minus 38 degrees Fahrenheit (minus 39 degrees Celsius). Sioux Falls, South Dakota, dropped to minus 26 Fahrenheit (minus 26 degrees Celsius).
Air travel was also affected. At midday, more than 2,700 U.S. flights had been canceled, led by more than 800 at Dallas Fort Worth International Airport and more than 700 at Bush Intercontinental in Houston.
Most government offices and schools were closed for Presidents Day, and authorities pleaded with residents to stay home Tuesday, too. About 100 school systems closed, delayed opening or switched to remote classes on Tuesday in Alabama, where forecasters said conditions might not improve until temperatures rise above freezing Wednesday afternoon.
Associated Press staff around the United States contributed to this report.