The individual motives for mass murder vary greatly. A common motivation is retaliation or revenge; others include grandiosity and the desire for attention or fame. On rare occasion, a mass murder occurs when the perpetrator, who may be deeply troubled, suffers a psychotic break from reality and strikes out at his perceived tormentors.
Unlike serial killers, mass murderers are frequently, but not always, killed at the scene of the crime. Sometimes they are shot by law enforcement officers called to the scene, while other times mass murderers take their own lives in a final and deliberate act of suicide.
Mass murder is frequently an act of vengeance against society committed by a desperate and fatalistic individual who has no intention of going away quietly or returning to kill another day.