(Missourinet) – The state Fire Marshall’s office says it can’t determine what caused the fire that killed four children late Tuesday night at a Lake of the Ozarks condominium.

Officials say the fire appears to have started just outside the door to the fourth floor unit the four children were in, but the damage was extensive enough it destroyed the evidence needed to pinpoint a cause.

The children who died have been identified as Kairi Helton and Zeza Bradshaw, both two, four-year-old Lee Ann Hendrickson and five-year-old Joshua Hendrickson.