"California, Los Angeles, Altadena, the Palisades - we are in this together," Green Day's frontman Billie Joe Armstrong screamed to a sold-out crowd at L.A.'s Kia Forum on Thursday for the FireAid wildfire benefit concert.

Green Day and Alanis Morissette set the tone at the FireAid benefit with songs of hope and resilience. Then came Anderson .Paak, who turned the stage at the Kia Forum into a California celebration, bringing out legendary musician Sheila E.

Billie Eilish made a surprise appearance on stage with Green Day on Thursday to kick off one of two star-studded concerts in Los Angeles put together to raise funds for people affected by deadly wildfires in California this month.