When Adam Lanza, 20, gunned down 20 children and six adults at the Sandy Hook Elementary School, the firearm he used was an AR-15 assault rifle.
The AR-15 was also employed by James E. Holmes, 24, the man accused of killing 12 people in a movie theater in Aurora, Colorado, July 20.
Jacob Roberts, 22, who shot and killed two people before taking his own life in a Happy Valley, Oregon, shopping mall on December 11, also used an AR-15.
read more