A similar incident occurred April 21, 2008. This incident was later revealed to be prank–flares attached to helium balloons.
Lights of varying descriptions were seen by thousands of people between 19:30 and 22:30 MST, in a space of about 300 miles, from the Nevada line, through Phoenix, to the edge of Tucson. There were two distinct events involved in the incident: a triangular formation of lights seen to pass over the state, and a series of stationary lights seen in the Phoenix area.
The United States Air Force (USAF) identified the second group of lights as flares dropped by A-10 Warthog aircraft which were on training exercises at the Barry Goldwater Range in southwest Arizona. Witnesses claim to have observed a huge carpenter’s square-shaped UFO, containing lights or possibly light-emitting engines. Fife Symington, the governor at the time, was one witness to this incident.