light hovered at low altutitude area close to mo/il border and shot upward at high speed.

A was taking a friend of mine home when we witnessed a light behaving as though it was a helicopter hovering at fairly low altitude with different, brilliantly, colored lights when it immediately shot upward at a speed which made it very hard to imagine it being a conventional aircraft.  At the time we were both high school students and dismissed it as something that was strange and interesting, but probably explainable.  The more we have talked about it, the more we feel it is worth consideration as a possible ufo. The main reason behind this posting is to see if maybe someone else observed this event.