Las Vegas police searched The Boulevard shopping mall Thursday night after reports of a masked person carrying a long gun prompted an evacuation.
Deputy Chief Chris Jones said a video was obtained showing the armed person. Police evacuated the mall and conducted three searches, but could not locate the person, he said. No shots were fired and no one was injured.
Boulevard mall manager Timo Kuusela said the incident started after reports that a man possibly carrying an assault weapon was spotted in the mall.
Multiple police cars and ambulances surrounded the mall.
"Police received a call and responded to the mall and evacuated the premises," Kuusela said. "Police have not located this person and they are clearing the building to make sure the person is not hiding inside."
As soon as the reports came in, police moved in quickly, authorities said.
"No person located with gun, no shots fired, no victims. Officers are clearing the mall as a precaution but at this point it all appears unfounded," the Las Vegas Metropolitan Police Department said.
In October, a gunman opened fire on concertgoers Las Vegas, killing 58 people in the deadliest mass shooting in modern US history.
Authorities do not know why Stephen Paddock fired hundreds of rounds indiscriminately from the 32nd floor of the Mandalay Bay hotel using a series of semiautomatic rifles, some outfitted with a device that allowed him to fire faster.