Police say a performance was underway at the Valley Fair Mall in West Valley City, Utah, when the loud noise sent people running for cover and hiding in stores.
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The mall was evacuated as police investigated.
Authorities later confirmed that the noise was caused by the falling sign.
Despite initial reports, police said no shots were fired and a fight had not occurred.
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No injuries were reported.
Two other incidents in New York and Louisiana also sent people running for safety Tuesday, days after mass shootings in El Paso, Texas and Dayton, Ohio left more than 30 people dead.
The loud backfiring of motorcycles mistaken for gunshots caused a widespread panic in Times Square, sending hundreds of people scattering.
Two men arguing at a Walmart in Louisiana pulled guns on each other, setting off a stampede of panicked customers, some of whom thought there had been a shooting. Baton Rouge authorities say a preliminary investigation did not find any evidence of a shooting, though an investigation is ongoing.
The Associated Press contributed to this story.