TMZ reported that Chester Bennington, the longtime lead singer and frontman for Linkin Park, was found dead Thursday of apparent suicide by hanging in his home near Los Angeles. He was 41.

The charismatic performer helped to make Linkin Park one of the most popular bands of the millennium; between 2000 and 2017, the group had seven albums reach the top three in the Billboard 200 (five of which reached the top spot), to go along with three top-10 singles. Their sophomore LP, Meteora, is one of the most successful and critically acclaimed alternative rock albums of all time, having been certified platinum four times by the Recording Industry Association of America.

Bennington was extremely close with Chris Cornell, former vocalist for Audioslave and Soundgarden. After hearing of Cornell’s suicide earlier this year, Bennington wrote an open letter to Cornell, praising the rocker’s talent and heart, which includes the line “I can’t imagine a world without you in it.” In addition to his work with Linkin Park, Bennington co-founded the band Dead By Sunrise and later spent two years touring with Stone Temple Pilots.

The singer has struggled with substance abuse and addiction in the past; in 2006, his usage and chosen lifestyle threatened both the future of the band and Bennington’s well-being. “I was on 11 hits of acid a day,” he told Metal Hammer. “I’d smoke a bunch of crack, do a bit of meth, and just sit there and freak out. Then I’d smoke opium to come down. I weighed 100 pounds … I knew that I had a drinking and drug problem, and that parts of my personal life were crazy, but I didn’t realize how much of that was affecting the people around me until I got a good dose of ‘here’s-what-you’re-really like.'”

A 2008 interview with Kerrang Magazine revealed a troubling history of sexual abuse in Bennington’s past, wherein an older friend began molesting him when the singer was seven years old. The abuse drove Bennington into depression, which he was only able to alleviate via substance use and abuse.

In recent years, Bennington has spoken about taking pride in sobriety, saying “We’re not a clichéd rock band where everyone is messed up on drugs. We’re decent people, so that makes me proud.” Linkin Park bandmate Mike Shinoda tweeted his reaction to the news, promising an official statement from the group eventually.

Shocked and heartbroken, but it's true. An official statement will come out as soon as we have one.

— Mike Shinoda (@mikeshinoda) July 20, 2017

Bennington’s body was found by an employee around 9 a.m. on Thursday; his family was reportedly out of town at the time. It is unclear if the singer had any drugs or alcohol in his system at the time of death, as no autopsy has been released of yet. Bennington is survived by his wife, Talinda, and his six children.