According to the Denver Post , seven concertgoers were injured early Sunday morning during Sound Tribe Sector 9’s performance at Red Rocks Amphitheatre. The incident occurred around 1am when several people were struck by falling rocks. Venue spokeswoman Kristin Rust tells the post that this was the first incident of its kind in at least 23 years. Denver police are reporting that four of the injured were taken to a nearby hospital, while the remaining three suffered minor scrapes and bruises. Unconfirmed reports from witnesses suggest that fans may have been climbing on the rocks prior to the incident.