Based on the number of events, their frequency and locations, arson is classified by type as single, double, triple, mass, spree or serial. The first three types describe a single fire set at either one, two or three locations, with no cooling off period. The characteristics of the others are: Mass: Three or more fires set at the same time in the same location. Spree: Three or more fires set at different locations, but with no cooling off period between. Serial: Three or more fires set at different locations, with a period of time passing between them.