A civilian biplane crashed at an air show in Northern California today, sending plumes of black smoke across Travis Air Force Base, KTVU reports. The crash occurred away from spectators, and no injuries were reported, but the pilot has not been accounted for. The Stearman plane was flying upside down and performing a maneuver called "cutting the ribbon" when it went down. An eyewitness video appeared on Instagram, reports NBC Bay Area, and an image was tweeted with the message, "This is not what you want to see at an air show." The show was canceled, and emergency responders are on the scene.