In preparation for a storm expected to bring 30 inches of snow to the greater Washington D.C. area, vehicle curfews have been imposed, flights delayed and public transportation closed. "An 'epic snowstorm' smacked the nation's capital and mid-Atlantic states Friday, and a father and son were killed on a slick highway in southwestern Virginia when they stopped to help another motorist. Virginia State Police said the weather-related accident happened early in the day on Interstate 81 in Wythe County. According to police, a car spun out of control in northbound lanes and came to rest in the left travel lane. A van carrying the father and son stopped on the right shoulder so one of its passengers -- a nurse -- could help the injured occupants of the disabled vehicle. Minutes later a northbound tractor-trailer came upon the disabled car. While trying to avoid hitting it, the truck jackknifed and struck the van. The father and son died at the scene, state police said. 'An epic snowstorm has the mid-Atlantic region in its crosshairs. At this time, personal safety must be first and foremost,' said a statement from Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration."