PORTLAND, Ore. -- Portland police arrested a 20-year-old man who was brandishing a replica gun while circling a rally in Downtown Portland on Monday.

Sergey Antonov, of Battle Ground, Washington, was booked into the Multnomah County Jail on a charge of second-degree disorderly conduct.

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At about 12:30 p.m., police were informed that a passenger in a truck had displayed a gun while driving past the peaceful demonstration at Terry Schrunk Plaza.

Officers located the truck and made a traffic stop at Southwest 4th Avenue and Salmon Street.

The driver and Antonov, who was the passenger in the truck, were both taken into custody. Officers found the gun inside the truck, which they determined was a replica firearm (BB gun). Officers also found an unloaded AR-15 style rifle inside the truck.

The driver, who owned the AR-15 style rifle, was released without charges, though the rifle was confiscated. Police said the driver can retrieve the gun at a later time.