The US capital Washington declared a state of emergency Tuesday as hurricane Florence moved closer to the east coast, threatening torrential rain and flooding in the region.
Mayor Muriel Bowser said the emergency was "effective immediately" and that the measure "ensures that we will have the resources we need to prepare for Florence".
More than a million coastal residents have been ordered to leave their homes ahead of the storm's projected arrival on Thursday, with emergencies already declared in the states of North and South Carolina, Virginia and Maryland.
The 15-day emergency signed by Bowser noted that Florence was "forecasted to produce high winds, rainfall and storm surge" with "serious widespread effects in the region".
The last time the US capital declared a state of emergency was in January 2016 when a winter storm dubbed Snowzilla blanketed the capital and its region in knee-deep snow.
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Hurricane Florence is the most powerful storm to threaten the Carolinas in nearly three decades.
Now a Category 4 storm with winds of 210 kph, it is expected to make landfall in North Carolina near the South Carolina border, the National Hurricane Centre in Miami said.
"This storm is not going to be a glancing blow. This storm is going to be a direct hit on our coast," said Jeff Byard, associate administrator for response and recovery at the Federal Emergency Management Agency. "We are planning for devastation."
The slow-moving storm was expected to strengthen with life-threatening storm surge possible along the coast. Residents boarded up their homes and stripped grocery stores bare of food, water and supplies.
In addition to flooding the coast with wind-driven storm surges of seawater as high as 3.7m, Florence could drop 51 to 76cm of rain in places, posing the risk of deadly flooding inland, forecasters said. They warned the storm could linger for days after making landfall.
Classified as a Category 4 on the five-step Saffir-Simpson scale of hurricane strength, Florence is the most severe storm to threaten the US mainland this year.
The United States was hit with a series of high-powered hurricanes last year, including hurricane Maria, which killed some 3,000 people in Puerto Rico, and hurricane Harvey, which killed about 68 people and caused an estimated $1.25bn (R19bn) in damage with catastrophic flooding in Houston, Texas.