The massacre in Orlando was the latest time an AR-15-style semi-automatic rifle was used in a mass killing.
The AR-15 was used to slaughter first graders at Sandy Hook, murder Batman fans at a Colorado movie theater and kill county workers at a holiday party in San Bernardino.
On Sunday, officials said a semi-automatic rifle was found amid the dozens of dead, and dozens of wounded, at the Pulse nightclub in Orlando, Florida.
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In the aftermath, President Obama once again railed at the ease with which domestic terrorists bent on killing as many people as possible can get their hands on high-powered guns and rifles.
Update: Authorities initially identified the rifle used in the June 12 Orlando shooting as an AR-15, but multiple sources now tell NBC News the gun was a Sig Sauer MCX, a similar semi-automatic rifle. This story has been updated to clarify.