RedactedNarrative: Operator #1 was sitting on seat of vessel #1, attempted to start jet ski. After 3'd time turning key, the vessel exploded. Operator was ejected into the air due to the explosion. The operator was transported to University of Toledo Medical Center with back injury. Damage to the vessel included a large hole in the hull which caused the vessel to sink. The vessel engulfed in flames, causing damage to the wiring, and the fiberglass on the front part of jet ski. The top half of the jet ski was blown apart from the bottom.