By law, the local fire department is responsible for determining the origin and cause of fires and explosions in its jurisdiction. The State Fire Marshal is mandated to investigate fires and explosions where local fire authorities are unable to determine the cause, where a violation of law exists, or when the fire or explosion is, or may be, arson. The Fire & Explosive Investigation Section of DFS includes the Fire Investigation Unit and the State Police Bomb Squad. Each unit has a self-contained command and control structure and serves a specific jurisdiction. Many investigators are cross-trained to assist other sections in time of need. Specially trained Massachusetts State Police detectives have functioned as State Fire Marshal investigators for more than fifty years.