SUMMARY: I and my brother were sitting on swings in a school playground, when a trianguler shaped object appeared.

It was around 8 o'clock pm (20:00) and my brother and I were sitting on swings in the Rocky Branch Elementry School playground, waiting for some of our friends.  It was dark out but the lights from the school lit up the playground.  Corn fields were on 3 sides of the school and a street to the other.  
We were sitting and talk when suddenly the silence behind us stopped.  We heard a soft humming like the sound the comes from one of those green power boxes (the big ones with the large hinges)   
Then a large triangular shaped object came from behind us (to the south).  It was about 100 ft. off the ground.  It had yellow flashing lights on each point.  
It stayed above us for about 2-3 mins then rapidly accelarated back to the south over a mountain.  After it burst away a very bright light shone for about a half a second.