Air Force One, with U.S. President Barack Obama aboard, arrives in the snow at Andrews Air Force Base, Md., on Saturday. (Alex Brandon/Associated Press)

A blizzard rocked the Mid-Atlantic and Northeast United States on Saturday, crippling travel across the region and causing hundreds of thousands of power outages.

Five deaths appeared to have been caused by the storm system, which stretched from the Carolinas north to New England and spread into some Midwestern states.

The 33 centimetres of snow that fell in Washington, D.C., by late afternoon was the most ever recorded for a day in December.

Earlier Saturday, snowplows cleared the runway at Andrews Air Force Base in suburban Washington as U.S. President Barack Obama returned from climate talks in Copenhagen.

The White House said Obama rode in a motorcade back to the White House, instead of taking his helicopter, because of the conditions.

Washington Mayor Adrian Fenty declared a snow emergency for the city and forecasters warned that conditions could worsen.

Philadelphia also declared a snow emergency and the school district cancelled all weekend activities. The storm was coating streets and highways in Philadelphia and the rest of southeastern Pennsylvania.

Forecasters said the storm system was expected to generate winds up to 55 km/h, which could cause near-whiteout conditions. Authorities in many areas asked drivers to stay off the roads if possible.

Officials at Dulles International and Reagan National airports warned travellers to check on the status of their flights before heading to the capital's airports.

Many Saturday flights along the U.S. East Coast were cancelled, and excessive delays were reported at airports in the Washington, D.C., area.

The storm system, coming from the Gulf of Mexico and spreading out across much of the Atlantic coastline, was forecast to bring a mix of snow and freezing rain to North Carolina, Tennessee and parts of western and central Virginia.

Several hundred motorists became stranded in western Virginia and had to be rescued by four-wheel-drive vehicles and Humvees driven by members of the National Guard.

Virginia Gov. Tim Kaine declared a state of emergency ahead of the storm. State police responded to hundreds of accidents statewide as snow accumulated on interstates and rural roads.

With files from The Associated Press