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.

One of the great challenges faced by the events during Grammy Week, including the FireAid benefit, is how to set the proper tone: How do you have a celebratory event like big concert or awards show without seeming tone-deaf to the tragedy and loss so many suffered in the Los Angeles wildfires that ravaged the

"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.