The incident happened just after 10 p.m. Tuesday near Old Fort Mountain.
Officials said the slide hit a car near mile marker 67.
"We were in fear for our lives," Lee Ribley, who was caught in the mudslide, told WLOS. "There was a very loud sound like a freight train."
Ribley said that was the last thing he and his fiancé remember before their car got swept away.
"Everything in front of us was just big turning mud," said Ribley. "There were big trees being pulled down into it and trees going through it and boulders."
Stay on top of breaking news stories with the ABC11 News App
Struck with fear, he said the few seconds felt like a lifetime.
"You see on television how there are victims of a disaster, then all of a sudden that was us."
He said when his car finally came to a stop, the danger continued.
"When the car stopped we told each other 'we're alive.' The fear of immediate death passed a little bit, but then we knew there could be more mud sliding down."
With nearly waist-deep mud surrounding the car, Ribley said they were stuck.
He said that's when they called 911.
"They came right to our aid," said Ribley. "They didn't stop and wait for equipment, they came right into the mud, linked arms and came after us."
Ribley said he's never been through anything like that before, which is saying a lot, considering Ribley has worked in law enforcement for 22 years.
"I was on the other side of it this time and those guys were heroes to me."