Sandy Hook shooting, Newtown, Connecticut: On 14th December 2012, the shooter who was identified as Adam Lanza, 20 years old, entered Sandy Hook Elementary School armed with bulletproof vest two semi-automatic handguns, a Glock and a Sig Sauer, as well as a semi-automatic rifle. He breached the school by shooting out a window pane of the front office, then gunned down and killed 26 people, including 20 first-graders and six adult school staff members. ( Photo | AP)