Storm surge and hurricane watches may be issued early Tuesday for portions of southeastern US states
Powerful Hurricane Florence headed toward the US East Coast on Tuesday, prompting authorities to order more than a million people to evacuate the path of the extremely dangerous storm forecasters said could soon intensify.
Residents scrambled to flee as the menacing Category 4 storm packing winds of 220km per hour moved closer.
"This is one of the worst storms to hit the East Coast in many years," President Donald Trump warned on Twitter. "Please be prepared, be careful and be SAFE!"
South Carolina Governor Henry McMaster ordered as many as one million coastal residents to leave their homes ahead of the storm's possible arrival on Thursday. Schools in 26 of the state's 46 counties were to close from Tuesday.
The governor of neighbouring North Carolina ordered an evacuation of the Outer Banks, barrier islands that are a popular tourist destination, and parts of coastal Dare County, while a state of emergency was declared in Virginia, where another 245,000 coastal residents were also ordered to evacuate.
"This is a very dangerous hurricane," McMaster said, adding that the evacuation order for coastal counties was "mandatory, not voluntary."
"We do not want to risk one South Carolina life in this hurricane," the governor told reporters. "We're liable to have a whole lot of flooding."
Trump approved emergency declarations for both coastal states, a standard move allowing the release of federal funds and equipment to aid in protection and recovery efforts.
The president said he had spoken with governors of threatened states, adding that the "federal government stands by, ready to assist 24/7."
Hurricane Florence has the potential to bring catastrophic flooding to areas of the eastern United States already soaked by heavy rain and it may be the strongest storm to hit the region in decades.
A Category 4 on the five-level Saffir-Simpson hurricane wind scale, Florence was 410 miles south of Bermuda and the centre of the hurricane was forecast to move between Bermuda and the Bahamas through Wednesday, and approach the coast of North Carolina or South Carolina on Thursday, the National Hurricane Center (NHC) said in its 0900 GMT advisory.
Forecasters expected some strengthening in the next 36 hours, as Florence marched west-northwest at around 13 miles per hour.
Storm surge and hurricane watches
At a hardware store in downtown Charleston, South Carolina, store manager John Johnson said the rush on batteries, flashlights, plastic tarps and sandbags began Friday.
"From eight o'clock 'til two we were slammed," said Johnson, who sold scores of bags of sand over the weekend, saving just a few to barricade the store's own doors.
"We were nonstop."
Storm surge and hurricane watches may be issued early Tuesday for portions of southeastern US states, the NHC said.
On its current track, Florence is expected to slam the Carolinas and Virginia the hardest.
The US Navy said it was preparing to send about 30 ships stationed in Virginia out to sea.
The vessels will get underway from Naval Station Norfolk and Joint Expeditionary Base Little Creek to avoid potential damage from winds and tidal surges, said Colonel Rob Manning, a Pentagon spokesman.
Heavy rain in the Washington area over the weekend has already led to flooding in historic Alexandria, Virginia, and the National Weather Service issued a flood watch for part of the Potomac River.