PHOENIX -- We're learning more about the men who died over the weekend after their ATV plunged 400 feet over the Mogollon Rim.
A Chandler High School student was killed in the crash, along with the driver who was a real estate agent from Glendale.
Coconino County Sheriff's investigators are still trying to figure out exactly what caused the crash. Officials have not released the names of all four victims, but family members confirm Rey Martinez was the driver of the ATV and 17-year-old Abraham Rodriguez Delgado was a passenger.
The teen's brother is now calling on U.S. Forest Service officials to implement safety measures on the dirt road, which hugs the edge of the Mogollon Rim.
A passerby on Rim Road captured video of smoke and flames in the area where the ATV went over the cliff. The person behind the camera had come across the scene shortly after the crash.
Gabriel Delgado says his brother, Abraham, was on that ATV. He was invited to go on a camping trip with his best friend's family.
"He loved the outdoors. He loved anything going fast, anything off-road. He was just a go-go kid."
The ATV driver, who relatives identified as Rey Martinez, was the stepfather of the teen that invited Abraham on the trip. A second ATV with other relatives also traveled Rim Road.
"The ATV that my brother was in got ahead of them.. several car lengths, I guess," said Gabriel. "We left that campsite on Sunday afternoon. We couldn't bring him back."
FOX 10 spoke with the driver's family and they declined to comment. Rey Martinez and his wife own a a realty business in Glendale. Surviving family members are struggling with grief. With one brother calling on forest agencies to make an effort to make Rim Road safer.
"Off-road vehicles are going up and down at whatever speed they like," said Gabriel. "Why isn't there a rail on that curve to avoid this kind of situation?"
CCSO says deadly accidents on the back roads of the Mogollon Rim district rae very uncommon.