COLUMBIA, Mo. (AP) — Two of five people from Kansas City remain hospitalized after their boat exploded on the Lake of the Ozarks.

The 25-foot Chris Craft boat exploded and caught on fire Saturday afternoon at the Millstone Marina & RV resort.

A preliminary report from the Missouri State Highway Patrol says the explosion apparently was caused by a build-up of gasoline vapors and a mechanical failure.

The Kansas City Star reports Ryan Baber, a family member, said the accident happened shortly after the boat was refueled.

A spokeswoman at University Hospital in Columbia says Baber’s sister, Cynthia Sterling, and her partner, Carl Harris, were both in fair condition Monday.

The couple’s 6-year daughter suffered burns. Barber said he and his father, Robert Baber, suffered minor burns and he has a sprained foot.