At least six people, including five children, were injured when a boat exploded just before noon Monday near Annapolis.

The 32-foot Wellcraft boat was heading into the South River after refueling at the Oak Grove Marine Center in Edgewater, just west of Annapolis, when one of the boat's two engines stopped working, said Lt. Jack Beall, a spokesman for the Anne Arundel County Fire Department. When the boat's operator tried to restart one of the engines, there was an explosion.

Of the nine people on board, at least six were injured, including all five children on the boat. A 9-year-old boy and a 9-year-old girl were flown by Maryland State Police helicopter to Johns Hopkins Bayview Medical Center in Baltimore; a 13-year-old girl was taken to Johns Hopkins Children's Center by ambulance; and a 9-year-old boy, a 13-year-old girl and a 31-year-old woman were taken to Anne Arundel Medical Center by ambulance. None of the injuries was believed to be life-threatening.

Two adults refused medical treatment. Beall did not know whether the last adult on board was injured.

The Maryland Department of Natural Resources and the Anne Arundel County Fire Department are conducting an investigation into the cause of the explosion. Preliminary findings lead officials to believe it was an accident, Beall said.