Authorities are still unsure of what killed a couple and their three children in their home in Springfield, Utah on Saturday night.

According to Springfield police, Benjamin and Kristi Strack, believed to be between the ages of 36 and 37, and their three children, son Benson, 14, daughter Emery, 12, and son Zion, 11, were found dead in their home at approximately 8:00 p.m. by their other son, who was not named, on Saturday, September 27. All five of the bodies were found in the parents’ bedroom.

Authorities have not ruled out foul play, but the preliminary autopsies did not show any signs of stab wounds, gunshot wounds or any other traumas to the bodies. Lt. Dave Caron said that there were no signs of a struggle and that they are hoping blood tests will help determine what caused the mysterious deaths.

“Preliminary autopsy results for the family of five who were found dead in their home have ruled out any sort of violent assault…The Medical Examiner has indicated that the next step is to continue the investigation through analysis of blood samples to determine what may have caused the deaths,” a press release that was released on Sunday said.

Pictured: Family found dead in Utah home with no signs of foul play http://t.co/pMohcvlXDY pic.twitter.com/HGylamOJfX

— Daily Mail US (@DailyMail) September 29, 2014

“We looked into the possibility it could have been carbon monoxide but we just don’t know at this point,” Caron said.

The family lived in a duplex, and the neighbor that lived on the other side of the wall spoke to the media and said that the police had checked their side of the duplex for high levels of carbon monoxide but did not find any elevated levels. However, they said that the CO could have dissipated before the test was done.

The investigation is still ongoing.