RedactedNarrative: Vessel 1 was north bound at idle speed traveling between the 2 ski point jetties.  When vessel 1 approached the east jetty, there was a loud explosion and flames and smoke started to become visible on the vessel.  Operator of vessel 1 was able to get all passengers off the vessel safely and extinguish the fire in the engine compartment.  Fire was most likely caused by ignition of unventilated fuel vapor inside the engine compartment.  Three of the five children on board received minor first and second degree burns and some singed hair and passenger/victim#2  was transported by private vehicle for treatment of a burn.  The boat was towed back to its trailer and removed from the lake immediately.  The poi was approximately 75 feet south of the public gas dock at the east jetty.