PIERRE, S.D. – Six members of a South Dakota family found dead last week in the ruins of their burned home were fatally shot, with one death believed to be a suicide, authorities said.

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

The deaths of Nicole Westerhuis and children Kailey, Jaeci, Connor and Michael have been ruled homicides, the statement said. The manner of death for Scott Westerhuis, Nicole Westerhuis’ husband, is suspected suicide, it said.

The Charles Mix County Sheriff’s Office and state investigators are looking into the circumstances of Scott Westerhuis’ death, according to the statement. Interviews, evidence collecting and forensic testing are ongoing. A spokeswoman for Jackley couldn’t immediately be reached for questions late Monday.

“Based on evidence of foul play continuing to be uncovered, law enforcement remains committed to a complete and thorough investigation,” Jackley said in the statement.

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

The Platte fire chief said the home was “pretty well destroyed” by the time firefighters arrived.

“It’s not a real common occurrence to have a fully engulfed structure fire on arrival,” Chief Rick Gustad said.

Authorities did not immediately name the victims, and Jackley’s statement Monday did not include their ages. But the Platte-Geddes school superintendent has said Kailey was a third-grader, Jaeci a fifth-grader, Connor an eighth-grader and Michael a high school sophomore.

Jackley called the deaths a “tragic loss” that has affected the entire community. About 1,200 people live in Platte, about 110 miles west of Sioux Falls.

Scott and Nicole Westerhuis both worked for Mid-Central Educational Cooperative, providing speech, language and hearing services to schools. The Westerhuis children participated in several activities including baseball, football, basketball, track, swim team, gymnastics and choir, according to a family friend.