There were four of us standing outside at around 4 pm on saturday, april 6, 2019 having a casual conversation and looking at contrails in the air running in different directions when one of us said 'whats that?' i looked up and at first thought it was three seagulls flying toward lake millerton. they appeared to have the same color combination but after observing them for a moment i realized they weren't flapping their wings. one of the observers noted that fact. the three craft flew in a nnw to sse direction, diamond formation, and did not vary in elevation or speed making no sound. we all three realized at about the same instant that these were not birds or conventional aircraft. they flew at about 60 degrees off the horizon and i would estimate were traveling at about 150 miles per hour give or take. my estimate would be at about 2500 to 3500 feet. at the end of the sighting the three craft made a slight left turn but stayed at the same altitude then left my sight due to light haze in the air. one of the four of us never picked up the sighting at all.