Billie Joe Armstrong and Billie Eilish. Green Day got things started at the Kia Forum, where they surprised fans with Eilish to help them perform, "Last Night on Earth" from 2009's 21st Century Breakdown.

The members of No Doubt -- Gwen Stefani, Tom Dumont, Tony Kanal and Adrian Young -- reunited at FireAid Thursday night and sang some of their biggest hits, including "Just a Girl," "Spiderwebs" and "Don't Speak."

The FireAid benefit was fueled by some of music’s best performers to raise money for Los Angeles-area wildfire relief efforts.