Shain Gandee, a castmember on MTV's Buckwild, was found dead Monday morning in a vehicle in Sissonville, W. Va.
The 21-year-old reality star's uncle, David Gandee, and a third person, who a source has identified as family friend Robert Myers, were also discovered dead in a 1984 Ford Bronco.
Brian Humphreys, the Public Information Officer of Kanawha County Sheriff Department, tells E! News, "There was no sign of foul play. Carbon monoxide poisoning seems plausible. The investigation is on-going."
The news, obviously, came as a shock to Shain's family, friends and fellow Buckwild castmembers. Many of them took to Twitter to reflect on the tragic loss.
"Everything doesn't happen for a reason," Buckwild's Katie Saria tweeted. "I don't know why people say that." The grieving reality star went on to thank fans for their condolences.
Shae Bradley took to Twitter to grieve as well, writing, "Breathe in. Breathe out. Repeat. Just going through the motions. Please pray for Shains close friends and family."
Buckwild's Anna Davis tweeted simply, "My heart is broken."
Fellow castmember Michael "Buckwild" Burford wrote: "My hearts in a million god damn pieces you son of a bitches wanna make smart ass remarks. I love you Shain idk what I'm gonna do w.o. ya bro"
"Rip Shain Gandee," Buckwild's Ashley Whitt wrote. "You are an angel, I know you will watch over me."
Other MTV reality stars tweeted their remorse about Shain's tragic death. JWoww tweeted it was "awful that Shain passed..." noting that he "was just a baby."
Pauly D wrote that Shain was "Too Young To Die !!!" and remembered him as "A Funny Dude."
Per Deadline, filming for the second season of Buckwild has been halted in the wake of Shain's death.
—Reporting by Ruth O'Neill, Sharareh Drury and Baker Machado