Triangular-shaped UFO spotted over Peoria, Arizona

On May 2, 2015, a teenage girl was in Peoria (in Arizona, USA) when strange lights were appeared across the sky. These three objects seemed to form a triangle. What is it?

Witness statement:

May 2, 2015 evening hours. Direction West by Northwest towards Luke Air Force Base, Glendale, AZ. from 75th Avenue and Thunderbird area. Lights were photographed by 16 year old daughter. A second attempted to photograph the lights was made, but disappeared at same time.