A huge snow storm in the north east of the US has caused whole cities to grind to a standstill. Snow-covered streets were almost deserted in the capital, where even the federal government has shut down its offices.Shops and museums were forced to close when around 30 centimetres of snow blanketed the Washington DC area, in a weather system affecting about 22 states and causing at least 18 deaths.A passer-by told euronews he had never seen snow in the capital before.Meanwhile, the National Weather Service has described the storm as an event of “historical proportions”. The cold weather front has even reached the generally mild south of the country, forcing the cancellation of around 6,500 flights.