DANA POINT, Calif. (AP) — A 25-foot powerboat sunk after it exploded and sparked a fire, damaging seven other boats at a Southern California marina, authorities said.

Witnesses reported hearing the blast around 9:30 a.m. at Dana Point Harbor’s West Basin, the Orange County Fire Authority said.

One person was assessed by paramedics, but declined to be treated or transported to a hospital, OCFA Capt. Thanh Nguyen told the Orange County Register.

An investigation is underway. The possible cause of the explosion could be gas fumes aboard the powerboat, said sheriff's Lt. Chris Corn.

Eight boats burned and three of them were destroyed, the fire authority said on Twitter.

Video tweeted out by the fire authority showed a vessel fully engulfed in flames and a plume of thick black smoke.

To the north, fire heavily heavily damaged two yachts docked at a Los Angeles harbor marina on Tuesday. That blaze was extinguished in about a half hour and no injuries were reported.