BUFFALO, N.Y. (AP) — A battering winter storm knocked out power to hundreds of thousands of homes and businesses across the United States on Saturday, left millions more to worry about the prospect of further outages and crippled emergency response efforts and an airport in snowbound New York state.

Across the country, officials have attributed at least 18 deaths to exposure, icy car crashes and other effects of the storm, including two people who died in their homes outside Buffalo, New York, when emergency crews couldn’t reach them amid historic blizzard conditions.

Deep snow, single-digit temperatures and day-old power outages sent Buffalo residents scrambling Saturday to get out of their houses to anywhere that had heat. New York Gov. Kathy Hochul said the Buffalo Niagara International Airport will be closed through Monday morning and almost every fire truck in Buffalo was stranded in the snow.

“No matter how many emergency vehicles we have, they cannot get through the conditions as we speak,” Hochul said.

Blinding blizzards, freezing rain and frigid cold also knocked out power from Maine to Seattle, while a major electricity grid operator warned the 65 million people it serves across the eastern U.S. that rolling blackouts might be required.

Pennsylvania-based PJM Interconnection said power plants are having difficulty operating in the frigid weather and has asked residents in 13 states to refrain from unnecessary electricity use through at least Christmas morning. The Tennessee Valley Authority, which provides electricity to 10 million people in Tennessee and parts of six surrounding states, directed local power companies to implement planned interruptions but ended the measure by Saturday afternoon.

Across the six New England states, more than 273,000 electric customers remained without power on Saturday, with Maine the hardest hit and some utilities saying it could be days before electricity is restored. PJM Interconnection also warned rolling blackouts might be required.

In North Carolina, 169,000 customers were without power Saturday afternoon, down from a peak of more than 485,000, but utility officials said rolling blackouts would continue for “the next few days.”

Those without power included James Reynolds of Greensboro, who said his housemate, a 70-year-old with diabetes and severe arthritis, spent the morning bundled beside a kerosene heater with indoor temperatures “hovering in the 50s.”

In the Buffalo suburb of Cheektowaga, two people died in their homes on Friday when emergency crews could not reach them in time to treat their medical conditions, according to Erie County Executive Mark Poloncarz. He said another person died in Buffalo and said the blizzard may be “the worst storm in our community’s history.”

Forecasters said 28 inches (71 centimeters) of snow accumulated as of Saturday in Buffalo — part of an area that saw 6 feet (about 1.8 meters) fall just over a month ago, resulting in three deaths. More is expected overnight.

The downfall blocked the furnace in the home of Brian LaPrade, who woke up Saturday morning to temperatures in his Buffalo house dipping to below 50 degrees Fahrenheit (10 degrees Celsius.)

“This morning I had to go out and dig out the vents,” LaPrade told the AP. “As it was, the snow was taller than my snow blower.”

It was taking ambulances over three hours to do one trip to a hospital, in areas where an ambulance can get through the snow, Poloncarz said. Plows were on the roads, but large snow drifts, abandoned cars and downed power lines were slowing progress.

On the Ohio Turnpike, four died in a massive pileup involving some 50 vehicles. A Kansas City, Missouri, driver was killed Thursday after skidding into a creek, and three others died Wednesday in separate crashes on icy northern Kansas roads.

A utility worker in Ohio was also killed Friday while trying to restore power, according to the Buckeye Rural Electric Cooperative. It said the 22-year-old died in “an electrical contact incident” near Pedro in Lawrence County.

A woman in Vermont died in a hospital Friday after a tree broke in the high winds and fell on her. Police in Colorado Springs said they found the dead body of a person who appeared to be homeless as subzero temperatures and snow descended on the region. Near Janesville, Wisconsin, a 57-year-old woman died Friday after falling through the ice on a river, the Rock County Sheriff’s Office announced.

In Lansing, Michigan, an 82-year-old woman died after being found Friday morning curled up in the snow outside of her assisted living community, Bath Township police reported. A snowplow driver found the woman as temperatures hovered around 10 degrees.

Kentucky Gov. Andy Beshear said one person died in a traffic accident attributed to the weather in western Kentucky and a homeless person died in Louisville.

Along Interstate 71 in Kentucky, Terry Henderson and her husband, Rick, were stuck in a massive traffic jam caused by several accidents for 34 hours. The truck drivers weathered the wait in a rig outfitted with a diesel heater, a toilet and a refrigerator but nonetheless regretted trying to drive from Alabama to their home near Akron, Ohio, for Christmas.

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

The storm was nearly unprecedented in its scope, 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.

As millions of Americans were traveling ahead of Christmas, more than 2,360 flights within, into or out of the U.S. were canceled Saturday, according to the tracking site FlightAware. While in Mexico, migrants camped near the U.S. border in unusually cold temperatures as they awaited a U.S. Supreme Court decision on pandemic-era restrictions that prevent many from seeking asylum.

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.

Western New York often sees dramatic lake-effect snow, which is caused by cool air picking up moisture from the warm water, then dumping it on the land. But even area residents found conditions to be dire on Christmas eve.

Latricia Stroud said she and her two daughters, 1 and 12, were stranded without heat or power in their Buffalo house since Friday afternoon, with the snow too deep to leave.

“I have to go over a snowbank to get out,” Stroud told the AP. “There’s a warming center, I just need a ride to get there.”