Unknown ignition source is what type of fire cause?

• A. Incendiary
• B. Natural
• C. Undetermined
• D. Accidental

Answer: (C)

When the ignition source can’t be identified from the investigation, the fire’s cause is labeled undetermined. In fire investigations, causes are categorized as natural, incendiary, accidental, or undetermined. A natural cause would be something like lightning; incendiary means deliberate ignition; accidental covers unintentional actions or equipment failures. If the origin and ignition source aren’t identifiable due to insufficient or inconclusive evidence, investigators mark it as undetermined. This keeps room for new information later, but at the moment of assessment the known evidence doesn’t point to a specific cause.