Authorities say the six members of a South Dakota family found dead in the ruins of their burned home were fatally shot, with one death believed to be a suicide.

The office of South Dakota Attorney General Marty Jackley said in a statement Monday night that preliminary autopsy results show all six members of the Westerhuis family died of shotgun wounds.

The statement says the deaths of the mother and four children have been ruled homicides. It says the manner of death for father Scott Westerhuis is suspected suicide.

An investigation into his death is ongoing.

Firefighters were called to the home near Platte early Thursday morning after a passer-by reported the blaze.

Fire officials said the home was nearly destroyed by the time firefighters arrived.