Heavy metal musicians and fans paid tribute to Slipknot star Paul Gray on Tuesday after the bass guitarist was found dead in an Iowa hotel room.

Gray, 38, was discovered by a staff member at a hotel in Johnston, near Des Moines, local police said.

An autopsy was conducted by the Polk County Medical Examiner's Office early Tuesday but police said in a statement the cause of death was still under investigation pending the results of toxicology tests in four to six weeks.

"The autopsy did confirm (an initial finding) that there was no evidence of foul play or trauma, and that Paul Gray had been dead for several hours before his body was discovered," the statement said.

Heavy metal musicians and fans reacted in shock to news of Gray's death Tuesday, which followed the recent demise of Black Sabbath's Ronnie James Dio and Type O Negative's Peter Steele.

Thrash metal band Sepultura said in a statement: "RIP Paul Gray, we're shocked and very sad. This is another tragic loss for our metal community."

Fans deluged a message board on the slipknot-metal.com website with tributes, many referring to themselves as "maggots" -- the affectionate moniker adopted by die-hard followers of the group.

"You will be dearly missed by the knot and all us maggots around the world," one tribute read. "I as a maggot salute you and you are and always will remain a big part of the Nine. Stay and god bless."

"I'm shocked and it's so hard to believe," another post read. "But people die, even metal gods. Rest in peace Paul."

Gray was one of founders of the nine-member Slipknot, which was launched in Iowa in 1995 and has become famous for the menacing hockey masks band members wear. Gray famously wore a black pig mask on stage.

While the masks have given the group a dark, macabre image, the band members said they were worn to allow the musicians a degree of anonymity while allowing their music to evolve.

Gray's face was largely hidden from public view. One of the rare photographs of the guitarist was from a mugshot following his arrest in 2003 for drug possession after he crashed his Porsche.

"Slipknot is my life," Gray once said in a rare interview posted on Youtube where he was filmed without his mask.

"It's everything. Without Slipknot I'd probably be sleeping on someone's couch, working at the old bar I used to work at."

Slipknot has enjoyed sustained success since their debut 1999 album, "Slipknot," which sold more than a million copies.

The band's fourth album -- "All Hope Is Gone" -- reached number one on the Billboard 200 in the United States and also topped the charts in Australia, Canada, New Zealand, Austria, Finland, Sweden and Switzerland.

The band has been nominated for Grammys on seven occasions, winning in 2006 in the best metal performance category for "Before I Forget."