According to the San Bernardino Police Department, Robert Andrew Medina was pulled over Sunday afternoon during a traffic stop.
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Police said officers conducted a search of the U-Haul truck and found an assortment of guns, including seven assault rifles, nine handguns, one shotgun, and 18 high-capacity magazines with assorted ammunition.
One of the firearms was found to be stolen while another had an altered serial number, according to police.
Medina was arrested on several felony weapons violation charges.
According to police, Medina had recently been arrested for a separate firearms violation.
He remains in jail on a $500,000 bond.