On March 13, 1997, the city of Phoenix located in the southwestern United States, state capital of Arizona and the sixth-largest city, became the location of one of the most important UFO sightings in history. Since the afternoon of March the 13th, people start seeing strange unidentified flying objects in the skies above the city. That night, thousands of people were witnesses to a huge triangular shaped object that apparently was levitating in the sky. People were able to identify between 7 and 9 intense bright lights and the mysterious object traveled more than 480 kilometers, from Nevada to Tucson.
While some accused the Luke Air Force Base of withholding information regarding the UFO sighting, others believed that Aircraft from the Luke Air Force Base were the cause.
Source and reference: The Black Vault