At about 1609 Eastern time, a Piper PA-30 crashed shortly after takeoff from the Fernandina Beach (Fla.)Municipal Airport. The airplane was substantially damaged and the commercial-rated pilot and one passenger were fatally injured. A witness reported the airplane was airborne with the landing gear retracted before reaching the intersection of Runways 04/22 and 08/26. He believed the airplane climbed to approximately 250-300 feet. Just before the airplane flew past a hangar, he heard a brief sputtering sound, then observed the airplane bank to the left. He then lost sight of the airplane for a short time as it passed behind the hangar. When he saw it again, the airplane was in a 25-30 degree left-wing-low and nose-low attitude, which continued until the airplane impacted the ground.