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."
MTV issued a statement saying it was shocked and saddened to learn of its star's death.
"We are waiting for more information but at this time, our main concern is for the Gandee family and their friends," the statement said. "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."
Shooting for the second season of "BUCKWILD" had begun, but MTV spokesman Jake Urbanski said Monday afternoon it has been suspended.
MTV said the half-hour series in the old "Jersey Shore" time slot 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. 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.
State Police say a multi-agency task force arrested Amin and two other people at a Summersville residence after receiving a tip from an informant. A search found oxycodone pills, heroin and $3,000 in cash.
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.
Associated Press Writer Vicki Smith contributed from Morgantown.