J. Sullivan, drummer for Avenged Sevenfold

A statement released by the Orange County coroner’s office said that Mr. Sullivan was found unresponsive inside his home and that no other information is available because an investigation is underway.

A spokesman for the Huntington Beach Police Department said there were no signs of foul play and Mr. Sullivan was pronounced dead at the scene.

“It is with great sadness and heavy hearts that we tell you of the passing today of Jimmy `The Rev’ Sullivan,’’ the other four band members said in a statement posted Tuesday on the group’s website. “Jimmy was not only one of the world’s best drummers, but more importantly he was our best friend and brother. Our thoughts and prayers go out to Jimmy’s family and we hope that you will respect their privacy during this difficult time.’’

James O. Sullivan was born Feb. 9, 1981, and befriended the future members of the group, whose name often is short-handed as A7X, while they were in high school.

Earlier this decade, the quintet built a strong local following playing in clubs and releasing recordings on small, independent record labels.

“The band seamlessly melds the epic mysticism and melody of vintage metal with startling, full-throttle punk grooves and shrieks,’’ Lina Lecaro wrote for the Los Angeles Times in covering one of the band’s local shows in 2004.

Expanding on that initial popularity, A7X established a national audience with the 2005 release of its major-label debut for Warner Bros. Records, “City of Evil,’’ which has sold just shy of 1 million copies in the United States, according to Nielsen SoundScan.

The band made multiple appearances on the Vans Warped Tour juggernaut of indie rock and found unlikely - for a metal band - success with such alternative and modern-rock outlets as MTV’s “Total Request Live’’ show and local radio powerhouse KROQ-FM with the breakthrough hit “Bat Country.’’ The group has now sold nearly 2.5 million albums since its first release.

Mr. Sullivan was in sync with his fellow band members by insisting that they weren’t interested in being pigeon-holed in any single musical genre, one reason the group shared a tour last year with Buckcherry, a band that has hewed closer to the rock mainstream.

“There’s a lot of straight-up rock mixed with a lot of metal fans, so it’s an interesting mix,’’ Sullivan told a reporter in Michigan last year.

The band has also developed, and then tried to distance itself from, a reputation for a wild lifestyle.

A 2005 Revolver magazine feature on the group quoted guitarist Zach “Zacky Vengeance’’ Baker as saying, “We love girls, we love music, we love booze and we love drugs,’’ and a subsequent piece in the same magazine described Mr. Sullivan’s zealous efforts to procure drugs.

“You can have a drink after a show, but I’ll never do anything before a show except warm up for an hour,’’ Mr. Sullivan told a San Antonio newspaper in 2006 in response. “We’re perfectionists when it comes to a live performance, because that’s what it’s all about.’’

Among the career highlights Mr. Sullivan cited was making contact with some of their childhood heroes, notably some tour dates the band shared with Metallica.

“And I got a big compliment from [Rush drummer] Neil Peart,’’ Mr. Sullivan noted three years ago, “who said something like I was one of the best-working drummers today.’’