Hurricane Irene ‘extremely dangerous’, says Obama

President Barack Obama warned Americans today to take Hurricane Irene seriously and urged them to obey orders to evacuate from the path of what is likely to be an "extremely dangerous and costly" storm.

"All indications point to this being a historic hurricane," Obama said in a statement to reporters from the farm where he is vacationing on this island off the Boston coast.

Fifty-five million people are potentially in Hurricane Irene's path, from the Carolinas to Cape Cod on the East Coast, and tens of thousands are evacuating as cities including New York and Washington brace for the powerful storm to hit.

Obama and his family will leave Martha's Vineyard on Saturday, well before Irene is projected to scour its way this far north on the New England coast. But the vacation had already been marked by natural disaster, after the island felt an earthquake in Virginia on Tuesday that shook Washington and New York.

Obama has held regular conference calls with aides on the storm, in a determined effort to learn from the mistakes of his predecessor George W. Bush, who was slammed for an ineffectual response after Hurricane Katrina swamped New Orleans in 2005.

"All of us have to take this storm seriously ... If you are given an evacuation order, please follow it," Obama said.