BUFFALO, N.Y. (AP) — Millions of people hunkered down against a deep freeze Sunday morning to ride out the frigid storm that has killed at least 24 people across the United States and is expected to claim more lives after trapping some residents inside houses with heaping snow drifts and knocking out power to several hundred thousand homes and businesses.

The scope of the storm has been nearly unprecedented, stretching from the Great Lakes near Canada to the Rio Grande along the border with Mexico. About 60% of the U.S. population faced some sort of winter weather advisory or warning, and temperatures plummeted drastically below normal from east of the Rocky Mountains to the Appalachians, the National Weather Service said.

Some 1,346 domestic and international flights were canceled as of early Sunday, according to the tracking site FlightAware.

Forecasters said a bomb cyclone — when atmospheric pressure drops very quickly in a strong storm — had developed near the Great Lakes, stirring up blizzard conditions, including heavy winds and snow.

The storm unleashed its full fury on Buffalo, with hurricane-force winds and snow causing whiteout conditions, paralyzing emergency response efforts — New York Gov. Kathy Hochul said almost every fire truck in the city was stranded Saturday — and shutting down the airport through Monday, according to officials. The National Weather Service said the snow total at the Buffalo Niagara International Airport stood at 43 inches (109 centimeters) at 7 a.m. Sunday.

Daylight Sunday revealed cars nearly covered by 6-foot snowdrifts and thousands of houses, some adorned in unlit holiday displays, dark from a lack of power. With snow swirling down untouched and impassable streets, forecasters warned that an additional 1 to 2 feet of snow was possible in some areas through early Monday morning amid wind gusts of 40 mph.

Two people died in their suburban Cheektowaga, New York, homes Friday when emergency crews could not reach them in time to treat their medical conditions, and another died in Buffalo. Four more deaths were confirmed overnight, bringing the total to seven in Erie County, where County Executive Mark Poloncarz warned there may be more dead.

“Some were found in cars, some were found on the street in snowbanks,” said Poloncarz. “We know there are people who have been stuck in cars for more than 2 days.”

Freezing conditions and day-old power outages had Buffalonians scrambling to get out of their homes to anywhere that had heat amid what New York Gov. Kathy Hochul called the longest sustained blizzard conditions ever in the city. But with streets under a thick blanket of white, that wasn’t an option for people like Jeremy Manahan, who charged his phone in his parked car after almost 29 hours without electricity.

“There’s one warming shelter, but that would be too far for me to get to. I can’t drive, obviously, because I’m stuck,” Manahan said. “And you can’t be outside for more than 10 minutes without getting frostbit.”

Ditjak Ilunga of Gaithersburg, Maryland, was on his way to visit relatives in Hamilton, Ontario, for Christmas with his daughters Friday when their SUV was trapped in Buffalo. Unable to get help, they spent hours with the engine running in the vehicle buffeted by wind and nearly buried in snow.

By 4 a.m. Saturday, with their fuel nearly gone, Ilunga made a desperate choice to risk the howling storm to reach a nearby shelter. He carried 6-year-old Destiny on his back while 16-year-old Cindy clutched their Pomeranian puppy, stepping into his footprints as they trudged through drifts.

“If I stay in this car I’m going to die here with my kids,” he recalled thinking, but believing they had to try. He cried when the family walked through the shelter doors. “It’s something I will never forget in my life.”

The storm knocked out power in communities from Maine to Seattle. But heat and lights were steadily being restored across the U.S. According to poweroutage.us, less than 300,000 customers were without power at 8 a.m. EDT Sunday – down from a peak of 1.7 million. In North Carolina, less than 6,600 customers had no power – down from a peak of 485,000 or more.

Concerns about the need for rolling blackouts across eastern states subsided Sunday after PJM Interconnection, the mid-Atlantic grid operator, said its utilities could meet the day’s peak electricity usage. PJM had called Saturday for the 65 million consumers in its territory to conserve electricity because of struggles by some power plants to operate amid frigid temperatures.

Across the six New England states, about 121,300 customers remained without power on Sunday, with Maine still the hardest hit.

In New York, more than 39,000 households were still without power Sunday , including 27,000 in Erie County, as crews battled high winds and found substations damaged. Hochul said that even the National Guard, which now has 200 people on the ground and another 200 expected by Monday, struggled with getting stuck in the snow.

Storm-related deaths were reported in recent days all over the country: seven in Erie County, New York; 10 dead in multiple crashes in Ohio, including a pileup involving some 50 vehicles, a man whose sport utility vehicle ran into a snowplow and an electrocuted utility worker; four motorists killed in separate crashes in Missouri and Kansas; a Vermont woman struck by a falling branch; an apparently homeless man found amid Colorado’s subzero temperatures; a woman who fell through Wisconsin river ice.

In Florida, the thermometer plunged below freezing for the first time in almost five years at Tampa International Airport, and hit 43 degrees (6.1 degrees Celsius) in West Palm Beach, according to the National Weather Service. The temperature drop and freezing sleet was conducive to iguanas falling out of trees since the cold-blooded reptiles typically become immobilized in unusually cold weather.

Along Interstate 71 in Kentucky, Terry Henderson and her husband, Rick, weathered a 34-hour traffic jam in a rig outfitted with a diesel heater, a toilet and a refrigerator after getting stuck trying to drive from Alabama to their Ohio home for Christmas.

“We should have stayed,” Terry Henderson said after they got moving again Saturday.

In Buffalo, William Kless was up at 3 a.m. Sunday He called his 8-, 9- and 12-year-old children at their mother’s house to wish them Merry Christmas and then headed off on his snowmobile for a second day spent shuttling people from stuck cars and frigid homes to a church operating as a warming shelter.

Through heavy, wind-driven snow, he brought about 15 people to the church in Buffalo Saturday, he said, including a family of five transported one-by-one. He also got a man in need of dialysis, who had spent 17 hours stranded in his car, back home, where he could receive treatment.

“I just felt like I had to,” Kless said

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Bleiberg reported from Dallas. Associated Press journalist Mike Schneider in Orlando, Florida; Jonathan Mattise in Charleston, West Virginia; Ron Todt in Philadelphia; John Raby in Charleston, West Virginia; Marc Levy in Harrisburg, Pennsylvania; and Wilson Ring in Stowe, Vermont, contributed to this report.