Mass murder is when someone hurts or kills a lot of people all at once. This is very bad and scary because it can happen anywhere, like at schools, churches, or public places. People who do mass murders are usually very angry or sick in their minds, and they want to hurt others. It is important to remember that this is not something that happens often, and most people are good and kind. If you ever hear about a mass murder, it's okay to feel sad or scared, and you can talk to an adult you trust about your feelings.