Story highlights A passer-by notices a car parked 65 miles west of Knoxville and sees four bodies inside

Victims were males and females and "relatively young," a state investigative official says

"We don't want this to be the one" case that goes unsolved, Cumberland County sheriff says

A passer-by found four people shot dead Thursday in a car parked alongside a rural Tennessee road, a mystery that has left authorities scrambling to identify the victims and hunt for whomever is responsible.

The vehicle was spotted around 7 a.m. on Renegade Mountain, an area about 65 miles west of Knoxville. The bystander quickly called the Cumberland County Sheriff's Department, Tennessee Bureau of Investigation spokeswoman Kristin Helm said.

"They knew that nobody lives on that street, and (the car) just looked odd sitting there," Sheriff Butch Burgess told CNN affiliate WATE

The victims were males and female, all of whom were "relatively young," according to Helm.

"We are continuing to identify the victims as it is still an active crime scene," the spokeswoman told CNN on Thursday evening. "...We still are trying to identify a suspect."

Authorities hadn't established a motive either.

According to the Renegade Mountain Community Club , the area around where the bodies were found had been a retirement resort, a ski resort and a golf club, though it's now mostly home to a small number of families.

One such resident, Cynthia Benson, described the killings as "sad, scary."

"We've had little problems, but nothing major," she told WATE. "Nothing like this."

"Our community is close and family-like," the message read. "The victims' families are certainly in our thoughts and prayers."

Burgess vowed that authorities are using "every asset that we have" to track down those responsible.

"Knock on wood, we've not had any (cases) that (have) gone unsolved," he said. "And we don't want this to be the one that does."