US snowstorm leaves four dead, hundreds of thousands without power

At least four people have died and dozens more injured as a major snowstorm spanning seven states moves across the United States.

Several states from the Midwest to the mid-Atlantic were hit by the storm. The US National Weather Service (NWS) estimates that approximately 60 million people are affected by the storm.

A polar vortex that dipped south over the weekend blasted the huge swath of land with ice, snow and wind. A state of emergency was declared in Kansas, Missouri, Maryland, Kentucky, Virginia, West Virginia, Arkansas, Washington DC and parts of New Jersey.

The polar vortex of extremely cold air usually spins around the North Pole, but it sometimes plunges southward into Canada and the US, Europe and Asia. Studies have revealed that a quickly warming Arctic is partly to blame for the increasing frequency of polar vortexes expanding their reach.

Schools were closed in many cities across multiple states. Millions of students were forced to stay home as most districts in the states of Indiana, Virginia, Maryland, Kentucky, Missouri and Kansas cancelled classes or delayed them to Monday.

At least 250,000 homes were left without power or heating on Monday as heavy winds damaged infrastructure in its path.

The storm produced more than 6 inches (15.24cm) of snow in many areas across the mid-Atlantic region, including the US capital. The NWS warned that up to 12 inches (30.48cm) of snow are expected to fall from Ohio to Washington DC in the early hours of Tuesday.

The intense snowfall has made many roads treacherous. A layer of thin ice coats many roads and highways making it extremely slippery for cars and resulting in a large amount of road accidents.

Officials in Missouri reported more than 350 vehicle crashes which resulted