The governor of South Carolina on Monday ordered the mandatory evacuation of up to one million residents of the east coast of the state of the United States before the arrival of Hurricane Florence.
"This is a very dangerous hurricane," said Governor Henry McMaster.
"We do not want to risk a life in South Carolina in this hurricane."
Florence, a category 4 hurricane, is expected to make landfall in South Carolina or North Carolina on Thursday.
The National Hurricane Center (NHC) says that Florence has the elements of an "extremely dangerous" weather event, reports the BBC.
The office of Virginia Governor Ralph Northam described Florence as possibly the "most significant hurricane event in decades" and warned of "catastrophic floods in the interior, strong winds and possible widespread blackouts."
He added: "The biggest threat to life from hurricanes is not strong winds, floods are the deadliest result of these storms."
The US Navy UU He ordered the ships at his main base in Hampton Roads, Virginia, to put to sea, saying that "the predicted destructive winds and the tsunami are too large to keep the ships in port."
Heavy rains in the Washington area over the weekend had already caused flooding in the historic city of Alexandria, Virginia, local media reported, and the National Weather Service issued a flood warning for the Potomac River.
Florence was "rapidly strengthening", with maximum sustained winds increasing to 105 miles per hour, becoming a Category 2 storm, the second weakest on the five-level Saffir-Simpson hurricane scale.
"The center of Florence will move over the southwest Atlantic Ocean between Bermuda and the Bahamas on Tuesday and Wednesday, and will approach the southeastern coast of the United States on Thursday," the NHC said.
The storm moved west-northwest at about nine miles per hour, and was predicted to soak a large swathe of the east coast of the United States from northern Florida to New Jersey.
In its current layout, Florence is expected to hit the Carolinas and Virginia stronger, and all three states have issued emergency statements to speed up preparations.
Two more hurricanes
The North Carolina governor's office, Roy Cooper, said Florence is already sitting along the coast of the state, with large swells resulting in rip currents and waves that threaten life.
"Everyone in North Carolina should closely monitor Florence and take action now to prepare for the impacts by the end of this week," Cooper said.
The storm "is too powerful and its path is too uncertain to take a chance," said South Carolina Governor Henry McMaster, issuing his state's emergency declaration.
Florence was producing large waves that are expected to arrive from the northern Caribbean to the southern coasts of the maritime provinces of Canada.
At this time of hurricane season in the Atlantic, two other hurricanes, Helene and Isaac, were dragging Florence along east-west paths.
Helene – 305 miles west of the Cape Verde Islands off the African coast – had winds of up to 85 miles per hour, and was expected to continue advancing west-northwest for a couple of days, said the NHC at its newsletter at 0900 GMT.
Hurricane Isaac, which on Sunday night became the fifth hurricane of the season, heads west toward the Caribbean.
At 0500 GMT Isaac, which the NHC called a small hurricane, was about 1,200 miles east of the Windward Islands, a region that is still recovering from last year's powerful hurricane Maria, with maximum sustained winds close to 75 miles per hour.
Isaac is expected to gain strength the next day or two before he begins to weaken in the middle of the week when he approaches the Lesser Antilles.
It is believed that Maria, who killed at least 3,057 people, the majority in Puerto Rico, is the third most expensive tropical cyclone in history.