A major winter storm is rolling across the central United States, bringing chaos among road and air transport users from Texas to Minnesota. At least 18 deaths were reported, many of them in Nebraska and Kansas due to icy conditions on roads. Some 100 flights leaving Minneapolis were cancelled. The US weather service said the storm was spanning two-thirds of the country. It advised against non-essential travel and scores of churches cancelled their Christmas services. Forecasters said up to 2 feet of snow were possible in some areas. A spokesman for the National Weather Service said the storm was moving from the Canadian border to Texas, extending from west Colorado to Illinois. He said freezing rain and high winds were making driving extremely dangerous. The storm began in the south-west on Tuesday, causing blizzard-like conditions and travel chaos, before spreading to the east and north. Flooding was predicted across Texas and into the Ohio Valley.