TREASURE ISLAND — Two people received minor injuries Friday afternoon when their boat exploded while docked at John's Pass Marina.

The 34-foot Formula cruiser had just fueled up and when the engine was started, the stern burst into flames, said marina manager Dana Robinson.

"It blew something off the back and it was smoking real bad," Robinson said. "The whole thing was on fire."

The two men on board quickly jumped into the water, said Treasure Island Fire Rescue Chief William Barrs. They were treated at the scene for minor injuries.

Ropes connecting the boat to the wooden dock burned through and marina staff pushed it away, Robinson said.

Ken Keller, who works at Gator's Cafe next to the marina, said he didn't hear an explosion but saw plumes of smoke coming from the dock.

"It was wild," Keller said. "It was really smoky, even when the boat floated away from the dock."

The cause of the fire is under investigation, Barrs said.