NINE of the 17 tourists who were killed after a boat capsized in Branson, Missouri were from the same family, it has been revealed.

The amphibious sightseeing boat capsized on Thursday amid high winds in what has become the deadliest accident of its kind in nearly two decades.

Seven of the 14 survivors were also hurt when the vessel went down, with at least two in a critical condition in hospital.

An initial assessment blamed thunderstorms and winds that approached hurricane strength, but it was not clear why the amphibious vehicle even ventured out onto the water.

Vigils have since been held in grief-stricken communities across the United States, with around 300 mourners turning out at the lake's car park.