SALEM, Mass. — When Adam Lanza slaughtered 20 first-graders and six staff members at the Sandy Hook Elementary School in Newtown, Conn., he used a Bushmaster AR-15 assault rifle to cause the carnage.
That's the same type of gun used to kill 12 people and wound dozens more in a July movie theater massacre in Colorado. It was used again this month to kill two people in a Portland, Ore., mall shooting.
This trilogy of killing sprees has ignited yet another national debate over the sale of semi-automatic weapons, with the AR-15 assault rifle front and center this time.
To many Americans, the AR-15 is a mystery. But not to the gun community. It is well-known there for its lightweight, durability and accuracy as well as the ability to fire multiple high-velocity rounds quickly.
Modeled after the U.S. Army's M-16, the user needs only to pull the trigger to fire each round after the weapon automatically readies itself to fire again from a high capacity bullet clip.
The rifle is commonly used by the public at shooting ranges, in marksmanship competitions and for hunting.
Lanza, the Connecticut killer, got the high-powered rifle from his mother, who had legally purchased it for shooting range practice. He murdered his mother before going to Sandy Hook School, and killed himself at the scene as police arrived.
That information has raised questions about what a military-style assault weapon with high-capacity ammunity clips is doing in a private home, accessible to a troubled family member.
But the AR-15 rifle, and versions of it, can be found in many homes across America.
Jim Wallace, executive director of the Gun Owners' Action League, estimated that "nationwide there's anywhere from 5 to 10 million of that rifle in the hands of lawful citizens."