LOST NATION, Ill. (AP) — A state fire investigator says the cause of a house fire that killed four children and two adults from the same northern Illinois family cannot be determined.

Sauk Valley Media reports Illinois State Fire Marshal's Office Arson Investigator Greg Castronovo wrote in his report that the home was so heavily damaged he couldn't examine all areas. The newspaper obtained his report Friday through a Freedom of Information Act request.

Arson is not suspected in the November 2017 fire in rural Lost Nation.

Authorities received a 911 call after midnight reporting smoke in the basement of the home outside Dixon. Firefighters arrived to find the house engulfed by flames. They later found the family inside, dead.

Killed were 39-year-old Timothy Shaw, 37-year-old Melissa Shaw, 17-year-old Ethan Shaw, 15-year-old LeAnne Shaw, 12-year-old Hailey Shaw and 11-year-old Dylan Shaw.