'Relentless rain' and strong winds are battering the state of North Carolina after Storm Florence made landfall.
Florence weakened from a hurricane to a Category One storm – however residents have been warned not to get complacent, with the weather system still bringing “life-threatening” conditions.
Police in the US state reported the first two deaths from the powerful storm, saying a mother and infant were killed after a tree fell on their home in the city of Wilmington.
The child's father was injured, and has been taken to hospital.
A woman who suffered a heart attack in Pender County died after emergency services were unable to get to her due to downed trees and debris, officials said.
US media also reported that a fourth person died when they were plugging in a generator.
Meanwhile, tidal surges and heavy rainfall have led to flash flooding, while winds of around 130km/h have caused significant damage.
The US National Hurricane Centre is warning of the potential for "catastrophic" flooding from lakes, rivers and freshwater reserves.
A tree uprooted by strong winds lies across a street in Wilmington, N.C., after Hurricane Florence made landfall. Picture by: Chuck Burton/AP/Press Association Images
CNN reports that more than 200 people had been rescued from rising water in the city of New Bern by mid-morning, with around 150 more waiting to be rescued.
At least 500,000 people were left without power, US media reported, while some areas reported 'major structural damage' to buildings.
Major structural damage to homes, businesses, and institutions are being reported around the Country.
— Onslow County (@OnslowPIO) September 14, 2018
Several more days of rain are expected after the storm made landfall early on Friday local time.
The hurricane's surge could cover large swathes of the Carolina coast, with surges as hihg as 11ft (3.3m) of seawater already reported.
Cameras outside the space station captured new views of a somewhat weakened #HurricaneFlorence at 6:56 a.m. EDT Sept. 13 as it neared the U.S. Eastern seaboard. According to the National Hurricane Center, Florence is moving northwest with winds of 110 miles an hour. pic.twitter.com/vw2yxrhTmZ
— Intl. Space Station (@Space_Station) September 13, 2018
North Carolina Governor Roy Cooper warned that the storm would continue to pummel the state for 'days'.
“This storm is going to continue its violent grind across our state for days. Be alert. To those in the storm path, if you can hear me – please stay sheltered in place. Do NOT go out into this storm.” - Gov. Cooper. pic.twitter.com/YEWgyCIJit
— Governor Roy Cooper (@NC_Governor) September 14, 2018
Earlier, he said: "Don't relax, don't get complacent. Stay on guard. This is a powerful storm that can kill. Today the threat becomes a reality."
He called for US President Donald Trump to declare a disaster to speed up the delivery of federal aid for clean-up and recovery after the storm passes.
“We know this massive storm will cause incredible damage and I’m asking Washington to act quickly so federal recovery help can come as soon as possible,” he said.
There are fears that this storm could cause damage similar to what Houston suffered during Hurricane Harvey last year, when homes and businesses were inundated with floodwater.
Ken Graham, the director of the NHC, said: "It truly is really about the whole size of this storm. The larger and the slower the storm is, the greater the threat and the impact - and we have that."
An American flag flies outside a row of vacant stores in Nichols, South Carolina, 13-09-2018. Image: David Goldman/AP/Press Association Images
On Thursday evening, Florence's forward movement was just 5mph. While hurricane force winds extended 128km from the centre of the storm, tropical storm force winds extended up to 314km. Overall, the storm is 644km wide.
Airlines have cancelled more than 1,500 flights, and coastal towns across the Carolinas are largely empty after 1.7 million people in three states were told to clear out.
One climate model is predicting that as much as 11 trillion gallons of rain will fall on North Carolina in the coming week - an amount that's enough to fill the Empire State Building 40 times over.
One electricity company fears that three-quarters of its four million customers will lose power as a result of the storm, and may not be reconnected for weeks.
Additional reporting by Stephen McNeice