There is "great debate" over the motivations of firefighter arsonists, according to the 2003 fire administration study, but they fall into a few general categories.

Perhaps the most common reason is excitement. "As much as it pains me to say this, they claim they were bored," Mr. Mann said. There is also a "hero syndrome" where "they want to be the first ones there."

Revenge, financial profit, vandalism and crime cover-up also are common motives.

These arsonists often had been with their department for less than three years. Typically, they have been white men ages 17 to 25 who come from dysfunctional homes, lack stable social relationships, work in menial jobs, and become firefighters for excitement more than public service, according to profiles developed by the FBI and the South Carolina Forestry Commission.