(CNN) -- Shain Gandee, one of the stars of the MTV reality show "Buckwild," and two other people died of carbon monoxide poisoning, the sheriff's office in Kanawha County, West Virginia, said Tuesday.
The deaths, discovered Monday, were labeled as accidental, according to preliminary findings from an autopsy report.
Gandee, 21, was found dead in a vehicle along with his uncle, David Dwight Gandee, 48, and Donald Robert Myers, 27, authorities said.
"This is a very sad and tragic event," Kanawha County Commissioner Kent Carper said Monday. "We live in a very small community. Our thoughts and prayers are with the Gandee family."
On Monday, the sheriff's office said they had "received word of a disabled vehicle in a wooded area" near Sissonville, that deputies and Sissonville Volunteer Fire Department personnel used all-terrain vehicles to reach the 1984 Ford Bronco belonging to the Gandee family.
"Inside were the bodies of three people," the sheriff's office statement said.
Later, the sheriff's office said the vehicle was partially submerged in mud. It was uneven but upright; its muffler was below the surface. Mud covered the lower part of the Bronco's passenger side door, but the driver's side, where the younger Gandee sat, was free.
Shain Gandee was one of the nine cast members of "Buckwild." The show follows a group of young adults trying to have fun in Sissonville, pulling stunts such as turning a dump truck into a swimming pool or just riding around the woods on their ATVs. Gandee was billed as a former high school prom king who had done "every job from coal mining to being a garbage man."
MTV released a statement about Gandee: "We are shocked and saddened by the terrible news about Shain Gandee, and those involved in this tragic incident. We are waiting for more information but at this time, our main concern is for the Gandee family and their friends. Our thoughts and prayers are with them. Shain had a magnetic personality, with a passion for life that touched everyone he met and we will miss him dearly."
Some of Gandee's fellow cast members took to social media to express their feelings.
"RIP Shain Gandee," Ashley Whitt tweeted. "You were the most amazing person I've ever known. I know you will be watching over ..."
"This is the emptiest I've ever felt," Cara Parrish tweeted. "Please pray for Dale and Loretta [Gandee's parents]."
"Buckwild" has been compared to MTV's reality show "Jersey Shore," and on Monday, one of that show's stars, Jenni "JWoww" Farley, tweeted, "That's awful that shain passed... He was just a baby. Rip. #Buckwild."