This story was updated on Monday, October 2 at 11:22 pm
On Sunday night, authorities said a gunman opened fire on a crowd of music-festival attendees from a room on the 32nd floor of the Mandalay Bay Resort and Casino in Las Vegas. The suspect, 64-year-old Stephen Paddock, allegedly shot and killed 58 people in what has become the deadliest mass shooting in American history—firing at a rate that set this incident apart from other recent shootings.
Las Vegas Police said Paddock was found dead when a SWAT team entered his hotel room, where investigators also reportedly found up to 20 firearms. (Las Vegas police have not yet released details of the firearms involved.) Semi-automatic guns shoot only one round for every pull of the trigger. Military-style automatic rifles and machine guns are able to fire multiple rounds per trigger pull.
On Monday evening, ABC News reported that a modified bump stock was recovered from the scene, and that authorities were still examining the weapons to see if any were capable of fully automatic fire. Bump stocks are legal, aftermarket accessories that allow semi-automatic weapons to fire at rates approaching those of fully automatic versions.
If the shooter used one or more automatic rifles—or even if it’s confirmed that he used legal accessories like a bump stock or trigger crank to approach their rate of fire, as some experts believe audio recordings suggest—it would mark a significant departure from other recent mass shootings.
Thirty years ago, the federal government identified automatic weapons for their unique ability to carry out mass casualty attacks and regulated them differently from other weapons, said Daniel Webster, the director of the Johns Hopkins Center for Gun Policy and Research. “As a result, [they haven’t] been used. Now there’s an exception to that.”