GARDINER — Two couples from Oakland escaped major injury Friday morning when the boat they were riding in exploded on the Kennebec River.

Sgt. Ken Grimes of the State Fire Marshal’s Office said the explosion occurred in the engine compartment of the 23-foot boat.

Shortly after 9:30 a.m., Vickie and Jeffrey Massey and Liliane and Howard Davidson launched the boat from the Gardiner public launch for a sun-splashed day on the river, according to Grimes.

The two men were sitting in the front of the boat and the women in the back, the sergeant said. A gasoline vapor in the engine that ignited was the cause of the explosion, Grimes said.

The couples jumped into the river to escape the flames, Grimes said, and a good Samaritan in a boat picked them up and took them to shore. The boat on fire beached itself on the opposite side of the river in Pittston.

The two women sustained minor burns and were transported to MaineGeneral Hospital in Augusta for treatment, while the two men were not injured.

“Although people did sustain some injuries when they went in the water, the injuries are not considered life threatening and everybody is safe,” Grimes said, noting the incident could’ve been more catastrophic.