INTERNATIONAL NEWS - Two officials told the Associated Press that two devices known as "bump-stocks" had been found along with 23 guns inside Stephen Paddock's room at the Mandalay Bay Resort and Casino.
It is not yet clear whether the stocks were fitted to the weapons that Paddock used in the massacre, but experts say they could explain the rapid rate of fire heard in videos shared on social media.
Audio analysis of one clip estimated that about 90 rounds were unleashed in only 10 seconds - far faster than a human being could repeatedly pull a trigger.
Since Congress passed the Firearm Owners' Protection Act in 1986, it has been extremely difficult for civilians to buy new, fully automatic weapons, which reload automatically and fire continuously as long as the trigger is depressed.
Thousands of "grandfathered" weapons manufactured and registered before then can still be bought, but they are very expensive and all sales must be approved by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).
