Billie Eilish joined Green Day on 'Last Night on Earth' to kick off the FireAid concerts in Los Angeles to benefit wildfire relief in the city.

FireAid, featuring Billie Eilish, Lady Gaga, Sting, Red Hot Chili Peppers and others in a fundraiser for Los Angeles-area wildfire relief efforts, is the latest event to combine music and philanthropy.

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.