Two vertical red blinking lights with two horizontal blinking blue lights which took off towards the west at speed.

At 5:50 pm, me and two witnesses saw red and blue blinking lights outside my sister's apartment hovering rock solid still, approximately 600 feet in the sky. We watched it and were amazed at how still it was. My friend said it looked like it was on a tower. But there are no towers near there. After about 5 minutes, we decided to leave and see if we could get closer. But as we walked toward my car, it took off at tremendous speed and was a solid, luminous blue as it flew away. There was never any sound. Could not see a solid object while it hovered. It looked solid blue when it took off. The shape seemed oval while it flew away. I did shoot it as it hovered, but if course, it was gone way too fast to whip my phone out again to get it while it flew away. My buddy was blown away and says he's a believer now. I don't know if my sister caught it taking off as she was leaving for another location. She called that location to tell them to film using a DSLR HD camera with a good zoom lens. I doubt they caught it.