What is the initial step in determining the origin of a fire?

The initial step in determining the origin of a fire is a preliminary scene assessment. This phase is crucial as it involves gathering first impressions and making quick observations that guide the subsequent investigation. During this assessment, investigators look for obvious signs of the fire's origin, the type of materials involved, and any potential hazards.

A thorough preliminary scene assessment allows investigators to prioritize their efforts and develop strategies for further examination, thereby establishing a clear foundation for the investigation. This initial evaluation might also include securing the scene to preserve evidence, which is essential for understanding how the fire began and progressed.

An in-depth interior or exterior examination generally follows the preliminary assessment. While these examinations provide detailed insights, they cannot occur effectively without the context and information gathered during the initial assessment. The fire spread scenario report, while valuable in understanding the fire's behavior and progression, also relies on the findings from earlier assessments to frame the analysis accurately.