Details weren't provided on the Rialto's website, but officials there said the date will be rescheduled by the middle of the week.
Meanwhile the band on its Facebook page posted this apology at 2 p.m. to Tucson fans:
"Tucson: We are sorry to announce the show tonight at Rialto Theater will be postponed due to mechanical problems with our Bus. We are working to find a new date for you and will update you ASAP. Thank you for your support."
Tonight's all-ages show with up-and-coming Cali duo Papa was to have started at 7 p.m.