(BAYVIEW, ID) — An Idaho Falls man and his grandson were injured in a boat fire in northern Idaho Tuesday afternoon. Officials say 70-year-old Richard Wagner and his eight-year-old grandson had to jump into Lake Pend Oreille because the boat exploded. Investigators believe it was caused by trapped fuel vapors in the engine’s bilge that weren’t properly ventilated when the boat was started. Both Wagner and his grandson suffered severe burns. Another person who arrived to assist them suffered minor injuries. Deputies say fast-acting bystanders helped keep the fire from spreading to the dock.