Following a Triangular UFOI was debating whether or not to report this because of the date of the sighting. Howevre I feel like it is important to report what occurred.I was on my way back to my girlfriends house after her, myself and our two friends went to a local store in Orland Park. She rode with our two friends and I drove by myself.I should mention a little about our background. I’m a student at a local college as is my girlfriend. My friend is the General Manager of a restaurant and his fiancée is a student also.I arrived at her house in Frankfort Square before they did so I waited in my car for them to arrive. As I was waiting, I received a call from my friend who was driving the car my girlfriend and his fiancée were in. He told me to drive to St Francis Road and turn east towards Harlem Ave. He said that there was a huge triangular object in the sky and I should be able to see it. I immediately did just as he said and the was a large triangular object in the sky.There were three lights on the object on each point and they appeared to be changing colors from red and blue constantly. The lights were far enough in the distance that the shape was not clearly visible but when the lights moved, they stayed the same brightness and appeared to be equidistant from each other. The object appeared at times to be pointing downward and then it would appear to turn and be pointing up or to the side.I told my friend that I saw it and we decided to see how close we could get to it. We decided to drive south on Harlem to Rt. 30 and head east. Two other cars appeared to have noticed it as they pulled over and were taking pictures on their phones. I got out my small video camera and attempted to record the object but it would not appear on my camera. I kept the camera rolling however to at least capture the audio of our conversation. My friend called both 911 and NBC5 news to report what we were seeing.My car got separated from theirs and they got close enough to the object where my girlfriend and my friends fiancée were both almost in tears because they were scared. They followed Rt. 3o to Indiana and when they got to the city of Dyer, IN, they reported that they had gotten really close to the object and then it disappeared. By this time I was about 5 miles behind them and I could see the object clearly as a solid triangular object. However when I got close to it, the object also appeared to just flicker out.I caught up with them in a parking lot in Scherriville, IN where my girlfriend got in the car with me and showed me some pictures she had taken on her phone. Only a single light was visible on all of her photos. As we talked in the parking lot about what had just occurred, my friends fiancée said that she “got a weird feeling that if we keep going east we will see it again.” I looked at her and my friend and said that we should probably head back home because I got a bad feeling about her last statement. However, my friend decide that maybe they should keep going east towards Merriville, IN.Well they decided to keep going east on Rt. 30 and my girlfriend and I decided to head north on Indianapolis Boulevard. We stopped at a bookstore so I could try to relax after what just happened. About 3 minutes after we had stopped at the bookstore, my friends fiancée called my girlfriend crying saying that the object did in face ‘reappear’ and it looked “a lot more menacing.” I told my girlfriend that I wanted to talk to my friend so she handed me the phone and I had his fiancée put me on the phone with him. He sounded kind of scared and he told me that he yelled at the object and the lights appeared to “flare up”. I kept talking to him as I went outside with my girlfriend and we saw the object to the south east. It appeared that there were one or two aircraft flying in the area of the object. I cannot say if they were commercial or military. I do know they were apparently circling and were flying pretty fast.My girlfriend and I got in my car and we drove south down Indianapolis Boulevard back to RT. 30 and headed east. I called another one of my friends from Valparaiso, IN to tell him what was going on and to keep a lookout because it appeared to be heading his way as my girlfriend talked to my other friends fiancée. They decided to turn around about half way to Merriville, IN. We followed the object to I65 in Merriville where the object vanished. We went home after that and my girlfriend was talking to my friends fiancée on the way home and all she kept saying was that she kept “wanting to look up”. We did notice that the aircraft that were circling the area were still there as we drove home on I80.The whole event lasted about an hour and a half. It was first noticed at about 8 :00 PM.