At 1437 Eastern time, the airplane collided with the ground after takeoff. Visual conditions prevailed; a post-crash fire destroyed the airplane. The Private pilot was fatally injured and one passenger received serious injuries. A witness observed the preflight inspection, engine start and taxi. A short time later the witness observed the airplane on its takeoff roll. The airplane did not seem to be going very fast, nor did it sound like the airplane was developing full power. The witnesss attention was diverted and, when he looked back, the airplane had disappeared from view. He then observed black smoke off the departure end of the runway.