saw saucer in large grass field it took off straight over vehicle went into sky and dissappeared

My father and I were returning from a hunting trip in Ukiha CA.  It was on a Sunday 5:30 p.m. on 101 hwy south.  We saw this shiny greyish object about 30 to 40 feet in diameter next to the edge of SanFrancisco Bay.  The reason why we noticed it was the field had caught a fire.  Then the object took off almost in a 45 degree angle straight toward us which was west and it was moving at such a great speed that after a few moments it just got smaller and smaller until it dissapeared.  The saucer was totaly quiet.  It had no lights that we could see and it left the grass field totaly burning.  My Father was an opperating engineer all his life.  He always wanted me not to talk about it because people would think that we were crazy or something.  And for myself I am 56 years old and don't care what they say.  My Dad is passed away so there is no one else that could back me up except if anybody like fire departments, the farmers, or anyone else that had seen the fire, or the saucer itselt.  I would like to know if there was a report around that area and time, that would make me feel a little better.  I am very mechanicaly inclined and know that this was not something that the US had developed for a few years later I saw the nasa research flying saucer in the old hanger at Mofet field in Mountain View CA and it was nothing in comparison to what my father and I saw.