Lane was found dead in a Comfort Inn hotel room in Woodland Hills, CA on Thursday, an LAPD officer confirmed to The AP.
The police spokesperson said that a cause of death has not yet been determined.
Lane is survived by two daughters from two prior marriages.
Fellow heavy metal singer Bret Michaels reacted to Lane's death by tweeting: "We'd like to offer our deepest condolences to the family of Jani Lane regarding their loss. Respectfully, Bret and all at MEGI."
Guns N' Roses guitarist Slash described Lane's passing as a "shame", while Motley Crue's Nikki Sixx wrote on Twitter: "I just heard the sad news about Jani Lane. So hard to swallow when people have kids. RIP."
Lane fronted Warrant on-and-off for more than 25 years, scoring five US Top 40 singles including the 1989 hit 'Heaven'.
In July 2010, Lane was sentenced to jail time for a DUI conviction.
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Watch Warrant's 'Heaven' music video below: