"We found those (missing) within the last hour," Missouri State Highway Patrol spokesman Jason Pace told AFP.

Pace said authorities were "in the process of making notification to the families."

The boat, one of two so-called "duck boats" that can float on water and drive on land, sank late Thursday on Table Rock Lake, a popular tourist spot in the midwestern US state, with 31 on board as a sudden and powerful storm moved in.

Authorities said children were among the dead, but the ages of the victims were not yet being released.