(CNN) 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 escaped the vehicle, a news release said. They have been placed on administrative leave, the HCSO said in a statement. CNN's request for the names of the deputies has not been answered.

Harrowing police scanner audio provides details of 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 victims were identified as Windy Newton, 45, of Shallotte, North Carolina, and Nicolette Green, 43, of Myrtle Beach. The sheriff's office characterized them as detainees.

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