SPRINGVILLE, Utah — A preliminary autopsy has ruled out any violent assault in the deaths of five Utah family members including three children, police said Sunday.

There was no evidence of stabbing or gunshot wounds or other visible injuries to the five found dead Saturday night in their home in Springville, about 45 miles south of Salt Lake City, investigators said. 

The five were identified Sunday as Benjamin Strack, 37, his wife, Kristi, 36, and three of their children, Benson, 14, Emery, 12, and Zion, 11.

Police Lt. Dave Caron said the cause of death has not been determined, and will not be until an analysis of blood samples is concluded. The medical examiner’s office provided no time frame for the release of results of laboratory testing.

While a test of air in the house by firefighters did not find any carbon monoxide, investigators have not ruled that out as the cause of death.

The front door of the house was open and the back door was cracked open before firefighters arrived, Caron said, and the gas could have ventilated before the test.

Asked whether foul play has been ruled out, Caron told The Associated Press, “I don’t rule out anything … We haven’t ruled out anything except there was no violent trauma. We’re going to look at everything.

“I do know when I was in there (house) I didn’t see anything that would suggest a struggle … I saw nothing like that,” he added.

The bodies were found shortly before 8 p.m. in the parents’ bedroom by an older son, who went to the duplex after he did not hear from the family as expected, according to investigators. His name was not released.

Caron said someone either saw or talked to the family Saturday morning, but he was unsure about the last person to make contact with them.

“It’s one of those things we’re going to take it one step at a time,” he said, adding the next step is to await the analysis of blood samples.

The duplex where the family lived is located on a road leading to a high school in the city of 30,000 located just south of Provo.