It has become the signature weapon of mass murderers in the United States, and it is capable of spraying targets with dozens of rounds from a single magazine.
AR-15 style rifles, the type used to kill 50 people in Orlando, Fla., on Sunday morning, have been used previously in mass shootings across the United States. From last year's terrorist attacks in San Bernardino, Calif., to the 2012 shootings at a cinema in Aurora, Colo., and the Sandy Hook Elementary School, killers have wielded the weapon with terrifying results.
In Newtown, Conn., Adam Lanza killed 27 people, 20 of them children, with an AR-15-style rifle, before taking his own life. After the tragedy, families of the victims launched a lawsuit against the rifle's manufacturer, Bushmaster Firearms, arguing that the company knowingly sold military weapons that are ill-suited for civilian use.
"There is one civilian activity in which the AR-15 reigns supreme: mass shootings," the plaintiffs wrote in their complaint. "Time and time again, mentally unstable individuals and criminals have acquired an AR-15 with ease, and they have unleashed the rifle's lethal power into our streets, our malls, our places of worship, and our schools."
The weapon, like most semi-automatic rifles, can be equipped with high-capacity magazines that allow shooters to fire more than 10 rounds without reloading. This, along with its immense popularity, has made it a target for gun-control activists, who say the rifle is too dangerous to be sold.
While officials in Orlando have not yet confirmed whether Omar Mateen, a 29-year-old U.S. citizen, used such a large-capacity clip, reports say more than 20 rounds can be heard in rapid succession in a bystander's video from Sunday's shooting.
AR-15-style guns' bloody history dates back to 1989, when California specifically banned the weapon along with other assault rifles in response to a deadly school shooting. But a legal loophole allowed manufacturers to continue selling it with a "bullet button," a mechanism that prevents users from reloading without using a tool.
In 1994, the U.S. Congress passed an assault weapons ban that prohibited manufacturing AR-15s for civilian sale with large-capacity magazines, bayonets or pistol grips. The ban limited sales of AR-15s, but did not end them. It expired in 2004, and efforts to renew the law have stalled in Congress.
Like most jurisdictions, Florida does not restrict the capacity of magazines, and attempts in other states to ban the clips by lawmakers largely have been ineffective.
In San Bernardino, California's tough gun laws did not stop Rizwan Farook and Tashfeen Malik from legally buying a pair of AR-15s before going on a shooting rampage that left 16 dead. The killers simply modified the rifles so they could be equipped with larger magazines.
Mr. Mateen legally bought the AR-15-style rifle, and a handgun, used in the Sunday's shooting, the FBI said.
With reports from the New York Times