A school shooting is an act of armed attack at an educational institution, such as a primary school, secondary school, high school or university, involving the use of a firearm. Many school shootings are also categorized as mass shootings due to multiple casualties. The phenomenon is most widespread in the United States, which has the highest number of school-related shootings, although school shootings have taken place elsewhere in the world. According to studies, factors behind school shooting include easy access to firearms, family dysfunction, lack of family supervision, and mental illness among many other psychological issues. Among the topmost motives of attackers were: bullying/persecution/threatened (75%) and revenge (61%), while 54% reported having numerous reasons. The remaining motives included an attempt to solve a problem (34%), suicide or depression (27%), and seeking attention or recognition (24%). Especially in the United States, school shootings have sparked a political debate over gun violence, zero tolerance policies, gun rights and gun control. The United States Secret Service published the results from a study regarding 37 school shooting incidents, involving 41 individuals in the United States from December 1974 through May 2000. In a previous report of 18 school shootings by the Federal Bureau of Investigation (FBI), they released a profile that described shooters as middle-class, lonely/alienated, awkward, Caucasian males who had access to guns. The most recent report cautioned against the assumption that a perpetrator can be identified by a certain 'type' or profile. The results from the study indicated that perpetrators came from differing backgrounds, making a singular profile difficult when identifying a possible assailant. For example, some perpetrators were children of divorce, lived in foster homes, or came from intact nuclear families. The majority of individuals had rarely or never gotten into trouble at school and had a healthy social life.