Smash Mouth frontman Steve Harwell launched into an expletive-laden tirade at a concert in Fort Collins, Colo., on Sunday.

The 90s rock band, best known for songs like "Walkin' On the Sun" and "All Star," was performing at the Taste of Fort Collins food and music festival when people started throwing pieces of bread onstage.

Harwell became enraged and video of the incident shows the 48-year-old hurling profanities at the crowd and threatening to "beat the f***" out of audience members.

"You're ruining the show for thousands of people right now," Harwell said during his rant. "I'm going to walk offstage, and guess what, you're paying for it motherf***er."

The crowd started booing and Harwell was escorted off stage by security.

Smash Mouth's last studio album, Magic, was released in 2012.