U.S. President Donald Trump on Wednesday toured areas of the Carolinas ravaged by Hurricane Florence as the death toll from the storm climbed to 37.

Trump sought to reassure those coping with the mounting disaster, saying during a visit to an emergency response center in South Carolina: "Washington is with you, Trump is with you."

Still, he cautioned: "You haven’t really been hit yet by comparison with what’s coming."

He earlier visited a devastated community along North Carolina's Neuse River, speaking to residents in the flood-ravaged town of New Bern.

"We’re giving you a lot of help,” Trump told one resident.

Two detainees died in Horry County, South Carolina when the sheriff's van they were being transported in was swept away by floodwaters overnight. The Horry County Sheriff's Office identified the deceased as Windy Newtown, 45, and Nicolette Green, 43.

North Carolina Gov. Roy Cooper continued to warn the state's beleaguered residents that for many areas, "the danger is still immediate".

"Flood waters are rising as rivers crest," he said during a press conference.

The Carolinas have been devastated by flooding brought on by Florence, which made landfall as a powerful Category 1 hurricane, with many areas bracing for what could yet be the storm's worst effects and a long-term recovery.

Environmental concerns continued to mount after massive industrial-scale hog and poultry farms in North Carolina were inundated by flood waters, causing toxic animal waste to pour out.

North Carolina's Department of Environmental Quality tracked 21 swine waste lagoons that were discharging into floodwaters and an additional 17 that were being inundated.