20+ red to orange lights (formation) seen in southern Minnesota sky. Three witnesses,While driving on the south central side of Austin, MN. in front of the water treatment plan, I noticed in the WNW skyline 3 reddish lights, stacked on top of each other. I thought it looked like cellular tower lights, but I was not aware of a tower in that area. I then noticed the three lights were moving toward me, from the low horizon, to about 45 degrees off the horizon, to overhead. As that group of 3-4 lights approached, the formation widened, and out of the same spot on the horizon, three to four more lights appeared, stacked like the others (looking like a radio tower). I pulled the car over, assuming these were formations of military helicopters. There were two other witnesses in the car.I stepped out of the car as the first group passed over head. I was surprised that the speed was faster than helicopters would be traveling, more the speed of jet aircraft. I am a private pilot, so have a good sense of speed and altitude. The first group appeared to be at a higher altitude as they passed overhead than I presumed, when I originally got out of the car. I would guess at 8,000 to 12,000 ft above the ground.As the first formation passed over head, the reddish color was now more of an orange color. There was no sound, which I found to be odd. The second group passed over about 10 seconds later. Same course and speed as the first. Then I noticed a third group coming up from the horizon, same spot. I then got back in the car, drove about a half block north, turned west on the next street and pulled over to see if more were coming. There were, no longer however in a formation (as the first three groups were). Now they were coming in line, about 5-7 second separation. I lost count of how many were passing over head in single file. I am guessing we saw an additional 8-12 objects pass over head. All at the same speed, same separation, course and same altitude.I noticed that the color changed from the initial view just above the horizon being reddish, to more orange as they approached over head. As they passed by, looking back the ESE, they were still orange, but a much dimmer and well defined spec of light. As the approached, the red was as bright as a radio tower light, as they got closer, and over head, as bright, but an orange color.The night sky was clear at the time, and visibility of the stars was excellent. There were no other lights on these aircraft, no red/green navigation lights or strobe lights, which I thought was odd, as even if these were military aircraft, they would typically have standard aircraft lighting on while flying in domestic US airspace.