A Massachusetts man was injured when his personal watercraft exploded as he started it on Long Lake in Naples.

The Maine Warden Service said Karl Marchionda, 31, of Danvers was thrown about 20 feet into the air Saturday afternoon when he started the Sea Doo watercraft after filling it with about 10 gallons of gas at Long Lake Marina.

Marchionda landed on the dock face-first. He was taken to Bridgton Hospital with injuries that were not life-threatening, mostly to his face. He was not burned, the warden service said.

The engine covering of the watercraft was thrown about 60 feet. Marina owner James Davenport quickly extinguished the fire in the hull of the watercraft.

Game Warden Neal Wykes said a lock ring securing the fuel lines to the gas tank had become loose and allowed some fuel to enter the hull.

The explosion was likely caused by fuel fumes when the machine started, but the incident is still being investigated.