Editor's note: Gun rights groups and individual owners lost a bid Monday to have the U.S. Supreme Court hear their challenge to strict bans on assault weapons brought by New York and Connecticut in wake of the 2012 Sandy Hook school shooting. The plaintiffs argued that the laws violate the Second Amendment, and pointed to the weapons' popularity among Americans. NBC News' Pete Williams notes the court has declined to hear challenges to local gun control laws since its landmark ruling on Second Amendment rights, in 2008. - Tricia
The Sandy Hook Elementary School shooting occurred on December 14, 2012, in Newtown, Connecticut, when 20-year-old Adam Lanza fatally shot 20 children aged between 6 and 7 years old, as well as six adult staff members. Prior to driving to the school, Lanza shot and killed his mother at their Newtown home. As first responders arrived at the scene, Lanza committed suicide by shooting himself in the head.
The incident was the deadliest mass shooting at a high school or grade school in U.S. history and the third-deadliest mass shooting by a single person in U.S. history. The shooting prompted renewed debate about gun control in the United States, including proposals for making the background-check system universal, and for new federal and state gun legislation banning the sale and manufacture of certain types of semi-automatic firearms and magazines with more than ten rounds of ammunition. A November 2013 report issued by the Connecticut State Attorney's office concluded that Lanza acted alone and planned his actions, but no evidence collected provided any indication as to why he did so, or why he targeted the school.