Thousands of people gathered in Manhattan's Washington Square Park. Students walked out of school to protest gun violence because of organizer Arielle Geismar. When she was 16 she started the organization New York Says Enough, a nonprofit dedicated to preventing gun violence and holding politicians accountable for tougher gun legislation. The 18-year-old says the mass shootings in El Paso, Texas, and Dayton, Ohio, unfortunately illustrate why she decided to take action.