The Bellagio hotel in Las Vegas was placed on lockdown following reports of an armed raider wearing a pig mask storming a Rolex store and "firing shots".
Reports of gunshots from those inside the hotel sparked widespread panic, though a Las Vegas spokesman said reports of an active shooter on site were false.
Police have confirmed that at least a burglar fired shots but there was no "active shooter". They have taken one person into custody for questioning while parts of the hotel remain closed off.
Guests said they heard the shots in the early hours of Saturday morning.