Autopsy results for two siblings who died in a bonfire explosion Saturday night were released Tuesday.

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"St. Clair County Medical Examiner Dr. Daniel Spitz determined the manner of death of Christopher Blewett was blunt trauma, involving the chest, primarily the heart," the St. Clair County Sheriff's Office stated.

"The manner of death of Savannah Blewett was blunt trauma to the head, including the face, primarily involving the brain," the Sheriff's Office said.

Toxicology results for this case are expected in approximately eight weeks.

Savannah Blewett was celebrating her high school graduation when the explosion took place. Although authorities initially said Christopher was 27, he was 26 at the time of his death. His sister was 17, not 18, as they initially reported, according to their funeral home obituaries.

According to St. Clair County Sheriff Tim Donnellon, the Sheriff’s Office Fire Investigation Unit conducted an investigation at the scene of the explosion in St. Clair Township. 

No criminal intent was found and the investigation has been closed.

"The cause of the blast was determined to be too much gas being placed on the wood prior to ignition," police said of the two-story bonfire. Christopher Blewett invited his sister to light the fire that then caused the explosion, police said.

Four people were injured, three of them were transported to local hospitals with non-life threatening injuries and the fourth person was treated at the scene.

Funeral services

Funeral services for Christopher and Savannah Blewett are scheduled for 11 a.m. Friday at Henry M. Malburg Funeral Home in Romeo. Rev. Jeffery Draeger of Our Redeemer Lutheran Church is to officiate. Visitation is from 2-9 p.m. Thursday. The siblings are survived by their parents Christopher and Jerrie (nee McDonald) Blewett and many other loved ones, according to the funeral home.

Christopher Blewett was a 2002 St. Clair High School graduate who loved 4-wheeling, snowmobiling and camping with friends and family. Savannah was passionate about photography, swimming, 4-wheeling and spending time with family and friends, the funeral home stated on its website.