Since 2006, guns have been used in an average of 25 mass killings per year in the United States, killing 2,596 people in all. We use the term “mass killing” to describe events in which four or more people died, not including the perpetrators. These violent episodes have occurred 10 times since the beginning of 2025. Some shooters target strangers in public, firing at children in schools, shoppers in stores, worshipers in sacred spaces.