Acclaimed heavy metal singer Warrel Dane, who achieved fame with the bands SANCTUARY and NEVERMORE, died on Wednesday (December 13) in São Paulo, Brazil. The American musician, who was in the process of making his second solo album, had a heart attack during the night and could not be revived.

Guitarist Johnny Moraes, who was a member of Dane's solo band, was with the singer around midnight when Warrel started to feel bad.

"He died in the night," Moraes told Brazil's UOL. "He was in the apartment where he stayed during the recording of the album when it happened. I gave him cardiac massage and we called the Mobile Emergency Care Service (SAMU), who came very fast, but when they arrived, he was already dead."

According to Moraes, Dane — whose Wikipedia page erroneously states he was 48 but who is believed to have been 56 — had a history of addictions and health issues. "His health was already very weak because of his diabetes and his problems with alcoholism," he said. "He was already facing a lot of health problems."

The instrumental parts for Dane's follow-up to 2008's "Praises To The War Machine" solo album were almost completed and he had begun laying down his vocals shortly before his death. The musicians in his solo band are thinking about finishing the record with guest singers as a posthumous tribute, but no decision has yet been made.

SANCTUARY guitarist Lenny Rutledge reacted to the news of Warrel's passing with a post on the band's Facebook page. "Today I wake up to the news that Warrel Dane has died," he wrote. "I don't even know what to say. My friend, brother and musical companion for over 30 years has passed away. I'm in total shock right now.

"I'm sorry for any close family or friends that had to hear the news on Facebook."

In a 2016 interview with Brazil's Imprensa Do Rock, Dane alluded to his alcoholism while answering a question about how he takes care of his voice. "The most important thing for a singer is you have to get a lot of rest, a lot of sleep," he said. "You have to drink a lot of water. You have to hydrate yourself. And you… I know I have a bad reputation about alcohol, but you kind of have to stay away. So I'm a little better now these days than I was. I know I have a bad reputation for drinking too much, but I don't so much anymore. And you just… you just have to realize your instrument and know your limitations and know your strengths. I used to, when I was younger, sing in the stratosphere — very high. As you get older, and I will completely admit this, I can't sing that high anymore. So now I focus on my strengths. And it's no secret that I'm a fan of goth music, so I love singing low."

NEVERMORE effectively split up in 2011 when guitarist Jeff Loomis and drummer Van Williams announced their departure from the band due to personal differences with Dane and bassist Jim Sheppard. Warrel later described NEVERMORE in an interview as "the greatest band that alcohol ever ruined."

Van wrote on Facebook earlier today: "So much to say, but can't find the words. Just solace in knowing we were friends again at the end of the day and that we enjoyed wayyyy more good times together than we did bad. Till we meet again, WD."

Loomis said in an Instagram post: "Rest in peace, Warrel. I will always cherish the good times we had together."

Dane told "The Jasta Show" last year that he "rarely" talked to Jeff, who is now in ARCH ENEMY. But, he insisted, "we don't hate each other. We're not enemies. We're still friends — friends that rarely speak to each other, unfortunately."

SANCTUARY, which reformed in 2010 after an 18-year break, has spent recent years touring in support of its comeback album, 2014's "The Year The Sun Died", as well as 2016's "Inception", an album comprised of presumed lost 1986 studio recordings.

A video interview with Dane conducted by Austrian web site We Don't Care at this year's MetalDays festival, which was held July 23-29 in Tolmin, Slovenia, can be seen below.