"Buckwild" star Shain Gandee, 21, was found dead, along with two other bodies, in a Ford Bronco at the end of a long dirt road in Sissonville, Ky.
The three men died of carbon monoxide poisoning, a West Virginia sheriff confirmed on Tuesday.
Their deaths have been ruled accidental.
The victims' bodies have been released to funeral homes, but no arrangements have yet been announced.
Kanawha County Commission Cpl. B.D. Humphreys said the body of Shain's uncle, David Gandee, 48, was also in the vehicle.The MTV reality star and his uncle had been reported missing on Sunday.
The third body was identified late Monday as that of Donald Robert Myers, 27, another Sissonville area resident.
Humphreys said the red-and-white 1984 Ford Bronco's muffler was below the surface and that mud covered the passenger side.
In lieu of the incident, MTV told FOX411 that the filming of the show's second season, which began a week ago, has been suspended.
“We are shocked and saddened by the terrible news about Shain Gandee, and those involved in this tragic incident," MTV said in a statement to FOX411. "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.”
Friends told TMZ that Gandee's family was having a hard time coming up with money for a funeral, so they were staging a charity "mud run" -- an off-road competition -- to help raise funds.
"Buckwild" premiered on MTV in January and follows nine friends in Sissonville and Charleston, West Virginia.Shain, nicknamed "Gandee Candy" by fans, was a breakout star of the show, which was filmed last year, mostly around Sissonville and Charleston. Many of its rowdy exploits were his idea. In one episode, he turned a dump truck into a swimming pool.
Gandee was a true outdoorsman, shedding modern conveniences such as cell phones and computers for his proud redneck ways. He loved to hunt, ride all-terrain vehicles and go "mudding," or offroad driving. He went mudding in the show's first episode and ruined his pickup truck's motor.
"Shain always rides with these kids in four-wheelers and trucks," said a neighbor, Swanna Frampton, who had known him since he was a small child. "They were just out riding and having a good time."
Frampton said Gandee "loved to live and have fun. He was a great person. He did what (the show) wanted him to do, but he wasn't like that. He was a real person. If you needed help, if needed something, he would come help you no matter what."
Humphreys said Gandee, his uncle, David Gandee and Donald Robert Myers were last seen around 3 a.m. Sunday at a bar and they told people they were going driving off-road.
State police were getting ready to send out an aviation unit to search for the men when authorities received a call Monday morning. Humphreys said the SUV was found by one of Shain Gandee's friends next to a trail used by four-wheel drive vehicles, about 15 miles outside of Charleston.
The terrain in the Thaxton Hollow area was "very muddy, very rough," Humphreys said, and responders had to use all-terrain vehicles to get to the site.
Humphreys did not provide details on the condition of the bodies.
Kanawha County Commission President Kent Carper said the news was devastating for the small community near Charleston.
"It's a very sad day for the Sissonville area and for these families," he said. "This is a small community, and most of us know directly members of these families. We're keeping them in our hearts and prayers."
The half-hour series, which took up the old "Jersey Shore" time slot on MTV, was pulling in an average of 3 million viewers per episode since its premiere and was the No. 1 original cable series on Thursday nights among 12- to 34-year-olds.
Shain Gandee is the third "Buckwild" cast member to make headlines.
Last week, 24-year-old Salwa Amin was sent back to jail for violating the terms of her bond following a February arrest. Amin, was arrested for stockpiling oxycodone and heroin with the intent to distribute. She was charged with two counts of drug possession with intent to deliver and initially jailed on $200,000 bond. That was later reduced to $100,000, but Amin remained behind bars without bond on Monday.
Another cast mate, Michael Douglas Burford, was charged in February with driving under the influence.
Urbanski said none of Gandee's cast mates was available to do an interview Monday, and none immediately planned to issue a statement. But their feelings came through on Twitter, where Ashley Whitt called her friend "the most amazing person I've ever known."
"I know you will be watching over me every time I hit a mudhole. You will always be my best friend, I love you!" she wrote.
Cast mate Cara Parrish and others asked fans to pray for Gandee's parents, Loretta and Dale.
"This is the emptiest I've ever felt," she wrote in a tweet.
"Buckwild" star Katie Saria added: "Thanks everyone for your condolences. We appreciate it. I guess what you do is pray."
The Associated Press contributed to this report.