While there was no active shooter, a high-end watch store at the property was burglarized by armed suspects, the Las Vegas Metropolitan Police Department's Lt. Carlos Hank told ABC News.
At no point were any firearms discharged, Lt. Hank said.
The Bellagio was on lockdown after the incident for about 30 minutes.
The store was not open at the time of the incident.
The suspects wore character masks, but Lt. Hank could not confirm the specifics of the mask. One eyewitness, though -- a woman named Kira, who did not want her surname used -- told ABC News she saw a man wearing a pig mask.
Lt. Hank said early Saturday morning that some people were detained, but it is unclear if the detained individuals are burglary suspects.
Police are continuing to search for suspects.
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