A "bomb cyclone" has unleashed hurricane-force winds and blizzard conditions in parts of the central United States, stranding travelers and leaving thousands without power.
A bomb cyclone occurs when there is a rapid pressure drop, with a decrease of at least 24 millibars -- a measure of atmospheric pressure -- over 24 hours.
In Colorado, the severe weather forced law enforcement officers to abandon their vehicles and take shelter instead of responding to motor vehicle accidents, officials said.