Over two million persons were ordered to evacuate from the US southeastern coastline ahead of the landing of Hurricane Matthew, with Florida's Governor warning residents to "prepare for a direct hit".
Residents of Georgia, South Carolina and Florida were braced for a possible impact from the storm, stocking up on supplies and boarding up homes, ABC news reported on Wednesday.
South Carolina Governor Nikki Haley planned to call for more evacuations, as Matthew is expected to be very near Florida's Atlantic coast by Thursday evening.
Florida had urged about one-and-a-half million residents to leave the coast, an official said, while the number in Georgia is around 50,000.
The National Weather Service (NWS) advised that "loss of life" and "immense human suffering" were possible from strong winds for those who did not take heed of the precautions.
"Catastrophic damage" is also a possibility, and the storm could "leave areas uninhabitable for weeks," the NWS announced on Wednesday.
Matthew struck the Bahamas after killing at least 22 persons in Haiti and four in the Dominican Republican on Tuesday. The storm weakened from a Category 4 hurricane after ploughing into Haiti and Cuba, where it left a trail of devastation.
Matthew was a dangerous and life-threatening Category 3 storm with sustained winds of 120 mph (190 kph) as it passed through the Bahamas.
The US military plans to send nine helicopters and 100 personnel to Haiti tomorrow to assist in aid efforts.
"In Haiti, the government reports that a number of persons have lost their lives and estimates that at least 350,000 people need immediate assistance," UN Secretary General Spokesman Stephane Dujarric said in a statement.
Some 80 per cent of homes were damaged in Haiti's Sud Department, which has a population of over 700,000, a government official said in a meeting with UN officials. Some 11,000 persons were in shelters in the province, the Telegraph reported.