Squadron of 12 triangular objects flying in linear formation

On the night of Tuesday, November 23, I took my dog out for the last time before bedtime. I saw a squadron of 12 triangular objects flying from west to northeast at approximately 10,000-15,000 feet altitude. They were flying in a linear formation in groups of 3s, 2s and 1s. They were dark in color except for 3 large rectangular, non-blinking red lights along either side underneath. The lights extended from the nose to the tail touching each other. They were silent, absolutely no sound of engines. As each one approached a certain point in the sky, it totally disappeared. Unfortunately, I had left my cellphone inside and was unable to videotape the event.