GARFIELD TOWNSHIP, Mich. (AP) — Police say the mother was the last person alive in a northern Michigan house where a couple and their two young children were found dead in an apparent “homicide-suicide.”

Michigan State Police said in a news release Monday that 34-year-old Tamisha Mendenhall suffered a self-inflicted, fatal stab wound in the groin that pierced an artery.

Sgt. Scott Bates says the exact cause of death is pending for her 54-year-old husband, Jeffrey Allan Mendenhall, 6-year-old Thomas and 3-year-old Olivia. Troopers found their bodies Thursday in their Garfield Township home.

Police say in in a news release that preliminary autopsy results showed no signs of physical injury to the father and children.

Police say they found empty prescription medication bottles in the house and a helium tank in the children’s room.