A massive winter storm has dumped snow, ice and sleet across large parts of the US, knocking out power and grounding thousands of flights.
The storm stretches for more than 3,000km from Texas to the northeastern state of Maine, and forecasters have warned it could be several days before it abates.
Blizzard, winter storm and freezing rain warnings were issued for more than half of the 50 US states.
Tornadoes and major thunderstorms have been predicted along the southern end of the storm in Louisiana and Mississippi.
Officials warned the public to stay at home rather than try to brave the dangerous storm.
'Travel will be dangerous and life-threatening due to dramatically reduced visibilities and bitter cold wind chills,' the National Weather Service office in Iowa warned.
'If you become stranded expect to spend the entire night in your vehicle as rescuers likely will not be able to reach you.'
High winds and freezing rain has turned roads into ice rinks and knocked down trees and power lines.
By late last night, more than 60,000 customers had lost power in Indiana alone, in addition to 22,000 in Ohio.
Forecasts warned of extremely cold temperatures, blinding snow and massive drifts as high as 1.8m to 2.4m.
'Lurking behind this impressive winter storm is a powerful shot of Arctic air as a frigid surface high drops down from central Canada,' the weather service warned.
Wind chills were forecast to drop to as low as -30C in Colorado, Wyoming, Utah, Kansas, Iowa, Nebraska, Minnesota and even parts of Texas.
States of emergency were declared in Illinois, Indiana, Missouri and Oklahoma and the National Guard was called out to help rescue stranded motorists.
Emergency warming shelters have also been set up for people whose homes lost power.
Thousands of schools and government offices were closed, while many businesses shut down early.
FlightAware reported that airlines grounded nearly 6,500 flights yesterday - about 20% of US commercial flights - and protectively cancelled another 3,600 today.
