Kevin Costner on the stage collapse in Alberta

While Costner was not on stage at the time of the incident, rising country star Billy Currington was in the midst of his set. Before his tour manager could drag him to safety, the stage gave way. Currington suffered a mild concussion, as well as scrapes and bruises. His bass guitarist, Alex Stevens, was trapped under the debris, which crushed his arm. Stevens underwent surgery Saturday night and was expected to be released from the hospital today. Currington was released this morning. Headliner Gary Allan was not yet at on-site. Promoters have cancelled the remainder of the Jamboree, which would have featured Tim McGraw closing out the final installment of the four-day country music celebration.