SOUTH CAROLINA -- Two South Carolina mental health patients drowned in a prison transport van when floodwater from the aftermath of Hurricane Florence overtook the vehicle, according to the Horry County Sheriff's Office.
Two deputies were able to escape the vehicle, a news release said. Harrowing police scanner audio provides details into the efforts to save the women, who could be heard talking as rescuers scrambled to save them.
"Tonight's incident is a tragedy. Just like you, we have questions we want answered," Horry County Sheriff Phillip Thompson said.
The women were identified as a 46-year-old from Shallotte, North Carolina, and a 44-year-old from Myrtle Beach. The sheriff's office characterized them as detainees. They remained in the van as of early Wednesday, and Marion County Coroner Jerry Richardson said authorities would not be able to retrieve their bodies until at least noon.
Richardson provided the patients' names but not their spellings. Chief Deputy Tom Fox of the Horry County Sheriff's Office did not respond to an email request for the spellings.
The deputies were transporting the women from Conway, near the coast, to Darlington, about 65 miles northwest, on Tuesday night.
According to CNN affiliate WPDE, the women were being transported from a hospital in Loris and from the Waccamaw Center for Mental Health in Conway to McLeod Health Darlington, Fox said. In an email, Fox confirmed to CNN that the women were mental health patients headed to Darlington, but he declined to divulge from what facilities they were being transported.
As the van traveled down US 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.
"The two deputies attempted to extricate the persons being transported," the news release said. "Despite persistent and ongoing efforts, floodwater rose rapidly and the deputies were unable to open the doors to reach the individuals inside the van."
Asked how the women were restrained in the back of the van, Fox told CNN they were "seat belted."
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 dangerous, according to the release.
The river stands at more than 14 feet and is expected to reach 15.6 feet by Thursday night. Flood stage for the Little Pee Dee is 9 feet.
Police scanner audio captured by CNN affiliate WMBF indicates the floodwater carried the van through a bridge guardrail near the Little Pee Dee Lodge on the Nichols side of the river.
"The officers report they got out. The van is submerged, and they cannot get their inmates out," an unidentified person says.
Later, someone else reports, "We have the two deputies that are out of the van and are secure on the boat. The two inmates are in the back of the van -- are still in the van -- and they're talking, and they're working on getting them out now."
The coroner confirmed Tuesday night that the women had died.
The investigation has been handed over to the South Carolina Law Enforcement Division, the news release said.
Investigators are in the early stages of conducting interviews and gathering evidence, SLED spokesman Thom Berry said. Once the bodies are recovered, they'll be transported to the Medical University of South Carolina for autopsies, he said.