President Barack Obama is urging residents of the U.S. East Coast to take precautions now, ahead of a powerful hurricane he said is likely to be “extremely dangerous and costly.”

Mr. Obama said Friday that all indications point to Hurricane Irene being a “historic” storm. He said the nation has to be “prepared for the worst” and urged anyone given an evacuation order to follow it.

The hurricane is prompting Mr. Obama to return from his vacation a day early. He is leaving the Massachusetts island of Martha's Vineyard for Washington Friday night.

U.S. authorities fear Irene will cause widespread flooding and power outages. The storm has the potential to cause billions of dollars in damage.

The governors of seven states — stretching from North Carolina to Connecticut — have declared states of emergency to free up resources ahead of the hurricane, which is expected to make landfall in North Carolina on Saturday.

Hurricane watches and warnings have been issued for much of the East Coast, with authorities in some areas evacuating residents and tourists. Airlines have already canceled hundreds of flights, and train services in parts of the eastern region have been suspended.

An estimated 65 million Americans live in Irene's projected path.

Homeland Security Secretary Janet Napolitano said Friday that federal and local authorities are taking the storm “very seriously.” She said President Obama has directed agencies to ensure all the needed resources are available.

In New York City, the mayor ordered hospitals and nursing homes in low-lying areas to evacuate.

The threat of the hurricane also led organizers in Washington to postpone Sunday's dedication of a memorial to civil rights leader Martin Luther King, Jr.

Irene, currently a Category Two storm on a five-point scale of storm intensity, is expected to have an effect well inland, both from winds and flooding. The National Hurricane Center says the storm is now carrying maximum sustained winds of 175 kilometers an hour and is expected to strengthen as it nears North Carolina.

Forecasters expect Irene to produce rainfall accumulations between 15 and 25 centimeters. Some parts of the U.S. mid-Atlantic and New England regions are already saturated from recent heavy rains, which will increase the risk of flooding.

Irene is the first hurricane to seriously threaten the United States in three years. It has already killed at least one person in Puerto Rico and two in the Dominican Republic, and also destroyed homes in The Bahamas.