The identity of the 2 women has been made public, along with assurances from the Sheriff's Office that they were not, contrary to reports, shackled in the back of the van when the flood came. High-water rescue teams rescued the deputies from on top of the van.
Aides say President Donald Trump will visit North Carolina on Wednesday to see the damage.
Thompson said neither deputy had committed any significant past driving infractions in connection with their duties.
"We want those who are responsible to be held accountable", it reads in part.
The coroner in neighboring Marion County confirmed the two deceased patients were female, and the South Carolina State Law Enforcement Division is investigating the incident, according to the statement.
Thompson said the deputies tried to get Newton and Green out of the van.
That's according to documents obtained from the State Law Enforcement Division concerning 45-year-old Windy Wenton and 43-year-old Nicolette Green.
Fox says that the van was driving down Highway 76 in Marion county, about a half-mile from the Little Pee Dee river, when the van was overtaken by water. He said it's typical for deputies to transport mental-health patients, and restraints aren't used if the patients aren't a threat.
'They were trying to negotiate through fast-running water, and it just didn't work out, ' he said.
Floodwaters in North Carolina were still quite high as of September 19.
The deputies were transporting Green and Newton based on court orders from the staff at Waccamaw Center for Mental Health and a mental-health center in Loris, Thompson said.
The death toll from Hurricane Florence climbed to at least 37, and North Carolina's governor pleaded with thousands of evacuees not to return home just yet.
The Lumber River overflows onto a stretch Interstate 95 in Lumberton, N.C., Tuesday, Sept. 18, 2018, following flooding from Hurricane Florence.
The two individuals being transported were confirmed dead by the Marion County Coroner.
"I know for many people this feels like a nightmare that just won't end", he said. "Due to risky conditions and rising waters, additional search and rescue teams are arriving to assist in the recovery of the vehicle". In March, Christopher Bennett died after eating drugs and suffering medical issues, a SLED investigation found.
According to information from the South Carolina Department of Transportation, the portion of Highway 76 in the Nichols area was closed Tuesday night and had been closed for some time.