It happened on Highway 76 south of Nichols in Marion County.
The van was carrying the detainees to a different facility in Darlington, South Carolina when it was overtaken by flood waters on Tuesday.
"They got out and tried to open the van to get the ladies out", Thompson told reporters on Wednesday.
More miles of northbound Interstate 95 in SC, just south of the North Carolina line, have been closed due to flooding from Hurricane Florence, the S.C. Department of Transportation said Tuesday.
Harrowing police scanner audio provides details of the efforts to save the women, who could be heard talking as rescuers scrambled to save them.
Two deputies were able to escape the vehicle, a news release said. Richardson later told the Washington Post that sheriff's deputies often transfer mental-health patients saying, "It's a courtesy they do".
"We want those who are responsible to be held accountable", it reads in part. The deputies were rescued from the van's roof, police said.
Justin Bamberg, a state lawmaker and lawyer who has represented the families of several people injured or killed by law enforcement officers, said Wednesday he's perplexed by the decision to transport anyone in such uncertain weather conditions.
The SCDOT added the driver of the vehicle had to go around a barrier to get stuck where they were. "It's come up 2 feet since just last night". "I am not sure if it was the way the van was positioned against the guardrail or it was pressure from the water".
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 dam and roadway at Alton Lennon Drive in Boiling Spring Lakes, North Carolina is washed away.
As for Nicolette's sister, she has one question: "What would prompt you to endanger your life and the life of the people the back, why?" said Donnela.
The incident took place in Marion County. Due to risky conditions and rising waters, additional search and rescue teams are arriving to assist in the recovery of the vehicle.
As I mentioned, we have as many questions, this is the very reason SLED and internal agencies are established.
Bishop and Flood have been placed on administrative leave while three separate investigations are conducted into the deaths.