Harrowing police scanner audio provides details into the efforts to save the women, who could be heard talking as rescuers scrambled to save them.
Two mental health patients have been killed after the HCSO transport van they were in was overcome with flood waters, according to an Horry County official in SC.
As the van traveled down United States 76 - about a half-mile from the Little Pee Dee River, which separates Mullins from the town of Nichols - high water swept away the vehicle.
Thompson said he did not believe the women were in restraints in the back of the van.
"They're still under the water", Richardson told The Associated Press early Wednesday.
Richardson said the van came across rising water and was carried off the road.
"They were trying to negotiate through fast-running water, and it just didn't work out", said the coroner, Jerry Richardson.
In North Carolina, transportation officials Tuesday continued advising motorists who ordinarily might take southbound I-95 from Virginia to SC that flooding has made long sections of I-95 in North Carolina impassable.
Holden said that deputies tried to get the victims out but couldn't.
Rescue teams were able to save the deputies from the van's roof, but they could not pull the vehicle from the water because it was too unsafe, according to the release.More news: Disney plans to launch Marvel Cinematic Universe streaming spin-offs
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According to ABC affiliate WPDE, the patients were being transported from Loris Hospital Waccamaw Center for Mental Health to McLeod Health, which runs multiple facilities in the region.
In the statement provided by police, HCSO cited two state laws saying officers are "authorized and required to take into custody and transport [the person] to the hospital designated by the certification".
Recovery efforts were underway Wednesday, said Thom Berry, a spokesman for the South Carolina Law Enforcement Division.
The dam and roadway at Alton Lennon Drive in Boiling Spring Lakes, North Carolina is washed away.
SLED, the South Carolina Highway Patrol and the Horry County Sheriff's Office are investigating the incident.
"We are sorry", Thompson said".
"We want answers", Green's sister, Donnela Green-Johnson, said in a Facebook post. The two deaths will push Florence's toll across three states to almost 40 victims.
State officials in North Carolina now say 3.4 million chickens and 5,500 hogs have been killed in flooding from Florence.
Boats are sunk and aground at Carolina Beach after the hurricane swept through.
Wilmington is still mostly an island surrounded by floodwaters, and people are waiting for hours for handouts of necessities like food.