KALAMAZOO (WKZO) -- Kalamazoo Department of Public Safety Assistant Chief Brian Uridge says the fire at Interfaith Homes that killed three children between the ages of one and three was not arson.

The department issued a statement Thursday saying the fire remains under investigation, but started "with human involvement."  The children were in the apartment alone when the fire started.

Investigators have ruled out weather, natural gas, water heater, furnace or electrical issues.