Slowly, the fire service is shedding light on a situation that occurs rarely but which is nevertheless serious: some firefighters intentionally start fires. A very small percentage of otherwise trustworthy firefighters cause the very flames they are dispatched to put out. The incidence of illegal fire setting among the nation's fire and rescue personnel is not known precisely. Fire incident data does not generate many details about incendiary fires, and a suspect's occupation is rarely, if ever, included in the database. Overall, relatively little research has been conducted on arson compared to other types of crimes. Even less information data is available about arsonists who are also public safety personnel.
Federal Emergency Management Agency: US Fire Administration, http://www.usfa.fema.gov/