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.

Audiences tuning into the FireAid benefit concert for Los Angeles on Thursday night (Jan. 30) were surprised with an early treat when pop superstar Billie Eilish made a surprise appearance alongside Billie Joe Armstrong and the rest of Green Day for a stirring opening performance.

"From the bottom of our hearts, we love you Los Angeles," Billie Joe Armstrong told the crowd, "and we've got your back no matter what"

Billie Eilish and Finneas, Olivia Rodrigo, Earth, Wind & Fire, Gracie Abrams, Green Day, Jelly Roll, Joni Mitchell, Katy Perry, Lady Gaga, Lil Baby, Pink, Red Hot Chili Peppers, Rod Stewart, Sting, Stevie Nicks and Tate McRae are among those performing at the dueling shows at L.