Two of the evening top-billed acts, Billie Eilish and Green Day, decided to sneak in an onstage duet. As the band geared up to play their beloved 21st Century Breakdown track “Last Night On Earth,” Eilish shocked viewers by picking up a microphone ahead of her set.

U2, whose members include Bono and the Edge, committed during the event to donating $1 million to the relief efforts. Steve Ballmer, former Microsoft CEO and current owner of the Los Angeles Clippers, and his wife, Connie, also pledged to match that donation and all donations made during the live broadcast of FireAid.

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

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 star-studded gigs were held simultaneously at the Intuit Dome and Kia Forum in Inglewood, California to help raise funds for the communities impacted by the wildfires that devastated the state earlier this month.

The massive LA wildfire benefit concert FireAid is happening in Inglewood right now at both the Intuit Dome and Kia Forum. At the latter, the night is starting off strong with Billie Eilish joining Green Day for 21st Century Breakdown’s “Last Night On Earth.

Some of the biggest names in music, including Billie Eilish, Lady Gaga, and Green Day, played FireAid at the Kia Forum and Intuit Dome on Jan 30.

"Part of the joy of being a musician is that you are a student"

Pop stars, rock legends, first responders, and survivors of the devastating Los Angeles-area wildfires came together for FireAid, a benefit concert to help the area recover. View on euronews

Just as FireAid hit the five-hour mark, Billie Eilish and her brother Finneas turned down the volume for an acoustic set as the night neared its end. Eilish had already made a cameo to set off the event earlier in the evening,

The all-star FireAid benefit in Los Angeles began with Green Day and Billie Eilish teaming up for the 'American Idiot' deep cut "Last Night on Earth."