Weapons and mass shootings

The Washington Navy Yard shooting a year ago that left 12 victims dead was one of more than five dozen mass shootings and spree killings in the U.S. since 1984. The shooter, Aaron Alexis, who also died, was armed with a legally obtained shotgun and a .45-caliber handgun taken from a security guard at the scene. Alexis had told police earlier that he’d heard voices, and had received mental health treatment.

Data collected by Mother Jones looking back at the weapons used in the last 30 years of mass shootings in the U.S. show that legal weapons are the norm.