Students across the country and the globe walked out of school Wednesday to demand action on gun violence and to honor the 17 people killed in the Feb. 14 shooting at Marjory Stoneman Douglas High in Parkland, Florida. From campuses battling snowstorms to schools that have seen their own fatal shootings, students left their classrooms for 17 minutes — one each for the dead in the Florida rampage. In all, more than 3,000 walkouts were planned, organizers said.