Shifty Shellshock,Oliver James Montgomery lead singer of the rap-rock band Crazy Town, has died. He was 49.

Shellshock, born Seth Binzer, died at a Los Angeles residence on Monday, according to Los Angeles Medical Examiner records. A cause of death is unknown at this time.

Crazy Town was known for the 1999 single "Butterfly," which reached No. 1 on the US Billboard Hot 100 chart in 2001. Their debut album, 1999's "The Gift of Game," sold 1.6 million units. The band broke up in 2003 after declining success in subsequent music projects.

The band included more than a dozen current and former members, including co-founder Bret "Epic" Mazur, DJ Rick One, Mark White, Adam "DJ Adam 12" Bravin, Charles "Rust Epique" Lopez and the late Adam "DJ AM" Goldstein.

USA TODAY has reached out to the LA medical examiner's office and Crazy Town's label.

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Binzer and Mazur reformed Crazy Town in 2007 and released an album in 2015. Mazur left the band in 2017, and Binzer changed the band's name to Crazy Town X.

Binzer appeared on the VH1 reality television series "Celebrity Rehab" Season 1 for cocaine addiction in 2008 and returned in Season 2 after producer and star Dr. Drew Pinsky learned of his relapse. The singer also appeared on the short-lived spin-off "Celebrity Rehab Presents Sober House" Season 1 in 2009 and Season 2 in 2010.

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Tributes came in on a post on Shellshock's Instagram page, which hasn't been active since April.

Photographer Mike Azira wrote: "RIP old friend… remember you best as a kid in a skateboard with the entire world in front of you… sending love to your family."