Members of the band, Russian Circles, say a thief broke into their U-haul truck early Sunday morning outside of the Holiday Inn parking lot in Chowchilla.
They say dozens of items, including electric and bass guitars, amps, pedals and microphones, were stolen.
The thieves also took the band's bicycle.
Anyone with information is asked to contact the band through their social media accounts.
Russian Circles just performed at the Save Mart Center on Saturday. They opened for System of a Down and Korn.