A colossal winter storm has hit the heartland of the United States, causing chaos on the ground and throwing air travel into turmoil.
States of emergency have been declared in Wisconsin, Illinois, Missouri and Oklahoma. The National Weather Service says this could be one of the biggest blizzards Chicago has seen in more than 40 years.
Up to a third of the US population is affected by the storm, stretching from Texas in the south to the northeast state of Maine. Power has been cut to hundreds of thousands of people.
And while motorists struggle to cope, thousands of flights have been cancelled.
Authorities have encouraged people to stay indoors rather than trying to brave the elements, with arctic temperatures and high winds to contend with as well as snow and ice.