My husband and i were returning home from a day in new braunfels/gruene area (about 30 miles north of san antonio) driving eastbound on interstate 10. i was on my facebook via smartphone until my husband who was driving asked me about these lights on the drivers side. i told him they were cell towers and waited for the car to position itself to see a shadow or outline of a pole....There was no pole. i said maybe it's a plane or a helicopter and then he commented on the light pattern was not characteristic of a plane or helicopter, since he was a ndt inspector in the us air force in the early 2000s and worked inspection off welds and aircraft issues all the time and is familiar with various aircraft. the lights truly looked circular, giving him and i the indication that this was no type of craft we've ever seen. we stopped at the nearest exit (exit 617-kingsbury) and proceeded to take pictures or videos with our camera phones (picture quality was extremely poor). to our amazement there were at least 20 additional crafts or lights at the time in perfect zig-zag formation and then gliding across both lanes of i-10 e/w in the night sky. as they glided away from the westbound lane one by one blinked and disappeared. i was flabbergasted and told my husband that this was impossible that any craft to just disappear. the next few moments of our encounter was just as exciting...Now the light/crafts were arriving in clusters of 3-4 at a time and disappearing just the same. my husband moved the car to get a better view of the southern horizon where the craft/lights were coming from and i noticed a pinkish/purplish hue of mist or smoke coming out of the treeline after the last one light disappeared. my husband was concerned that it was a fire and wanted to leave before it caught up to us.