Red flashing lights seen hovering over Washington University.

As I was drawing the blinds to our south facing window, I saw something hovering above the tree line, approximately 200-300 yards away over Washington University.  It had two blinking red lights and had drone like hovering.  It continued to go back and forth (east and west) and would sometimes dip below the tree line and disappear.  It did this for about 10 minutes and then took off flying northeast, at which time, we saw a small green light turn on.  It flew pretty closely past our house and no sound was heard.  We moved to the north side of the house and watched it fly out of sight and it disappeared.  If it was a drone it had a really long range it was operating in.