On this day, 2012, 20-year-old Adam Lanza killed 20 first graders and 6 staff members in Sandy Hook Elementary School. Lanza not only killed children and staff, but his mother and himself as well. Earlier in the day, Lanza shot and killed his mother in their home, and later himself when he heard police arriving at the school. The school was located in Newtown, Connecticut, and was razed in 2013 as a result of the shooting.

Information found on History.com.