U2's longtime tour manager died early Wednesday morning in Los Angeles ... just as the band kicked off a week-long string of concerts in the city.
Law enforcement sources tell TMZ ... Dennis Sheehan was found unconscious in his room at the Sunset Marquis Hotel. We're told paramedics were called to Sheehan's hotel room around 5:30 AM for a reported cardiac arrest. He was pronounced dead on the scene.
Sheehan -- who was in his late 60s -- has been U2's tour manager for more than 30 years.
His death came just hours after the curtain went down on U2's first of 5 concerts at the Forum in L.A.
Sheehan's been all over the rock n' roll scene since the '70s. In addition to U2 ... he worked with rock legends like Led Zeppelin, Iggy Pop, Patti Smith and Lou Reed.