At least 21 people were killed and millions left without power, water or gas as Hurricane Isabel swept through eastern United States, leaving widespread destruction in its wake.

Six million people were without power with no chance of restoration in a week. Over a million people in Virginia have been advised to boil drinking water.

The hurricane toppled thousands of trees at it moved through North Carolina, Virginia, the District of Columbia, Maryland and other states right up to New York, before shifting north and entering Canada Friday. It has since been downgraded to a tropical storm.

More than 300 trees were uprooted in the Washington area alone. Virginia Governor Mark Warner said it was "probably the worst (hurricane) in a generation."

Robert Dobkin, a spokesman for Pepco, the local electric company, said: "It is beginning to look like it will be the worst outage in our company's history."

Four hundred traffic lights were knocked out in the Distrit of Columbia.

Several areas remained under water today. Though it may take some time for normalcy to return, local train services have resumed and airlines promised that their services would be near-normal today.