A deadly blast of arctic air shattered decades-old temperature records as it enveloped the eastern United States this week, snarling air, road and rail travel, driving energy prices higher and overwhelming shelters for homeless people.

At least nine deaths have been reported across the country connected with the polar air mass that swept over North America during the past few days. Authorities have put about half of the United States under a wind chill warning or cold weather advisory.

Temperatures were 25 degrees to 35 degrees Fahrenheit (14 to 19 degrees Celsius) below normal from the Midwest to the Southeast, the National Weather Service said.

PJM Interconnection, the agency that oversees the electric grid supplying the mid-Atlantic and parts of the Midwest, said electricity suppliers were struggling to keep up with surging demand as the cold forced some power plants to shut.

Oil refiners were also hit, with Marathon Petroleum Corp and Exxon Mobil Corp both experiencing cold-related outages.

Major U.S. cities were in the grip of temperatures well below freezing, with Chicago seeing 2 degrees Fahrenheit (-17 C), Detroit 0 F (-18 C), Pittsburgh 5 F (- 15 C), Washington 19 (- 7 C) and Boston 15 F (- 9 C).

New York’s Central Park recorded the lowest temperature for the date, 4 F (-16 C), rising to 9 F (- 13 C) on Tuesday afternoon with wind chills making it feel much colder, meteorologists said.

At New York’s Bowery Mission homeless shelter, the 80-bed dormitory was full on Monday night and 179 other people slept in the chapel and cafeteria, officials said.

Impassable snow and ice halted three Chicago-bound Amtrak trains on Monday, stranding more than 500 passengers overnight in northwestern Illinois.

In the normally mild south, Atlanta recorded its coldest weather on this date in 44 years, as the temperature dropped to 6 degrees Fahrenheit (- 14 degrees Celsius), while temperatures in northern Florida also briefly dropped below freezing, though the state’s citrus crop was unharmed, according to a major growers’ group.

Among the deaths reported was a 51-year-old homeless man in Columbus, Georgia, whose body was found in an empty lot after spending the night outdoors.

Two men died in Westerport, Massachusetts, while duck hunting on Tuesday, January 7, when their boat capsized, dropping them into a frigid river, officials said. A third man was rescued.

A large avalanche in backcountry outside the Colorado ski resort area of Vail killed one person and caught up three others who survived and were being rescued, officials said. Avalanche danger in the area was rated as “considerable” due to high winds and recent heavy snows, said Spencer Logan, forecaster with the Colorado Avalanche Information Center.

Four cold and storm-related deaths were reported around Chicago and an elderly woman was found dead outside her Indianapolis home early Monday.

The cold snap could cost the U.S. economy up to $5 billion, when lost productivity and lost retail sales are accounted for, estimated Evan Gold, senior vice president at Planalytics, which tracks weather for businesses. He said about 200 million people in major cities might face “bill shock” for heating.