Police have identified the names of two South Carolina women who drowned inside a sheriff's transport van, revealing that the victims were not inmates and had been seeking help for mental illness.

Horry County Sheriff Phillip Thompson said Wednesday that the two women killed are Wendy Newton, 45, and Nicolette Green, 43.

They died on Tuesday after the Horry County Sheriff van they were in drove into floodwaters near the Little Pee Dee River in Marion County. The two deputies traveling in the van survived after escaping and waiting on the roof of the vehicle for help.

It was previously reported that the women were inmates and were being transported from Conway to Darlington on Tuesday night, days after Tropical Storm Florence battered the Carolinas with torrential rain and heavy winds.

Nicolette Green (left) and Wendy Newton (right) drowned in a sheriff's transport van on Tuesday night

The women were being taken from the hospital to a mental health facility when the van drove into floodwaters. Pictured is the highway where the van was traveling

Responders congregate Wednesday near where two women drowned near the Little Pee Dee River

Officials in South Carolina were keeping a watch on several rivers known to flood, including the Little Pee Dee River.

Thompson said Newton and Green were mental health patients and were being taken from the hospital to a facility in the city of Florence when the van became engulfed by water.

According to the sheriff's department, Newton and Green were seated in the back of the van. Thompson said he does not believe they were shackled or in police restraints.

He said the two deputies, identified as Joshua Bishop and Stephen Flood, tried to help free Newton and Green from the van 'for a long period of time' but eventually had to seek refuge on the vehicle's roof as the floodwaters continued to rise.

'I'm not sure if it was the way the van was positioned, against a guardrail, or if it was pressure from the water, but unfortunately they were not able to get the van doors open and get the ladies out,' Thompson said Wednesday.

The sheriff said the part of the highway where the van became submerged was blocked off. He said it appears the deputies drove around the barrier, but the investigation is ongoing.

'It hasn't been confirmed to me that they did, but here's my questions: There's barriers there. It could be assumed that he did,' Thompson said.

According to the South Carolina Department of Transportation, the portion of Highway 76 where the van was was closed on Tuesday night. Officials told WMBF that it had been closed for some time.

The sheriff said he does not believe Newton (pictured) and Green were shackled or restrained in the van

Green had three children, her family said and had been diagnosed with schizophrenia three years ago

It took a rescue crew 45 minutes to find the submerged van. The deputies were plucked from the roof and taken to safety via a boat. According to CBS, by the time crews reached the women the van was underwater.

Joshua Bishop (pictured) escaped the van with another deputy and waited on the roof for help

Because of the dangerous conditions, rescuers were not able to retrieve the bodies immediately and they were pulled from the water on Wednesday evening, nearly 24 hours later.

'We're sorry. We take a lot of pride in what we do. We work hard to protect and to serve our citizens, and we're just so very sorry that this event has taken place,' Thompson said.

Green's family told CBS that she had three children, but one died in 2015 from cancer.

'We want those who are responsible to be held accountable,' the family said in a statement. 'These woman were not inmates or criminals. They were women who voluntarily sought help. They trusted the hospitals and sheriff deputies with their lives and that trust was abused. We want answers.'

Her 19-year-old daughter Nicolette Hershberger said Green had been diagnosed with schizophrenia three years ago and had went to a new therapist on Tuesday. The therapist had commanded Green be committed to a mental institution.

The part of the highway where the van was at had been closed because of the rising water of the Little Pee Dee River (pictured in a September 17 photo)

'I was confused as to why someone would, or the police officers would drive down a road that was in an area that was known for flooding,' she told NBC.

'The fact that they (the deputies) were able to get out but my mom and the other woman wasn't makes me feel really like hurt and betrayed by them.'

The drowning is being investigated by the State Law Enforcement Division and Highway Patrol. Thompson said there is also an internal investigation and the deputies involved were placed on administrative leave.