What factor may indicate that arson is involved in a fire?

When evaluating fire incidents for potential arson, the presence of unusual difficulty in attacking the fire can be a significant indicator. This could suggest that the fire has been deliberately set or manipulated to create obstacles for firefighters. For example, if fire fighters encounter barriers that would not typically be present in ordinary fire scenarios—such as locked doors, blocked access routes, or unusual use of materials that enhance fire behavior—these factors can imply intentional actions taken to hinder suppression efforts.

In contrast, while elements like the presence of multiple heat sources, rapid spread of the fire, and high levels of smoke production may all be associated with certain fire dynamics, they do not inherently indicate arson. These factors can occur in fires resulting from natural or accidental causes as well. The primary distinction with unusual difficulty in attacking the fire is that it may reflect purposeful interference or manipulation, which aligns closely with behaviors typical of arson cases.