|New York Mayor Bloomberg has ordered unprecedented evacuations for a quarter of a million people [Al Jazeera]
Hurricane Irene has spread inland over southeastern North Carolina in the US Atlantic coast, triggering emergency preparations that included unprecedented mandatory evacuations in Washington, Baltimore, Philadelphia, New York and Boston as the massive storm approached.
Washington and states from the Carolinas through Maine declared emergencies due to Irene, a nearly 960 km-wide hurricane that forced 55 million Americans on the eastern seaboard to prepare for and that experts say could cause billions of dollars in damages.
A hurricane warning was in effect from North Carolina all the way to Massachusetts - including for New York City, where more than a quarter-million people were ordered to evacuate ahead of Irene's arrival on Sunday. It was the first hurricane warning issued for New York City in more than two decades.
Officials called up hundreds of National Guard troops, shut down public transit systems and begged hundreds of thousands of people to obey evacuation orders, starting in east North Carolina where the hurricane was expected to make landfall on Saturday morning.
Defence Secretary Leon Panetta said the military stood ready to aid in the response to Irene, with more than 100,000 National Guard forces available if needed in East Coast states.
Coastal communities stocked up on food and water and tried to secure homes, vehicles and boats. Cities, ports, hospitals, oil refineries and nuclear plants activated emergency plans.
As US authorities ramped up preparations to cope with a potential major natural disaster on the densely populated East Coast, US airlines cancelled more than 3,000 flights and moved airplanes out of Irene's path.
‘Dangerous and costly’
Irene weakened early on Friday to a Category 2 hurricane from a 3 on the five-step Saffir-Simpson scale, but it still was carrying winds of up to 155 kph per hour.
It was expected to remain a hurricane as it sweeps up the mid-Atlantic coast over the weekend. The Miami-based hurricane center said it could dip below hurricane strength before reaching New England, but its impact would not change much.
Ed Rappaport, the deputy director of the National Hurricane Center, speaks to Al Jazeera from Miami about the impending storm
President Barack Obama said the impact of the storm, which is unusually large, could be "extremely dangerous and costly" for a nation that still remembers destructive Hurricane Katrina in 2005.
"All indications point to this being a historic hurricane," Obama said.
Irene, the first hurricane of the 2011 Atlantic season, had already caused as much as $1.1bn in insured losses in the Caribbean this week, catastrophe modelling company AIR Worldwide said, with more losses expected to come.
Flooding from Irene killed at least one person in Puerto Rico and two in Dominican Republic. The storm knocked out power in the Bahamian capital, Nassau, and blocked roads with trees.