The 15-year-old arrested after a shootout at food festival near Seattle's Space Needle over the weekend was armed with a ghost gun with an extended magazine, police said Tuesday.Police Chief Shon Barnes told a news conference th at the weapon was a 9 mm gun from Polymer80 a now-defunct company that was once a leading manufacturer of ghost gun parts.RELATED STORY | Court documents say there were at least 3 shooters at Seattle festival, 1 deadInvestigators also recovered two other weapons and 14 shell casings that had been fired by weapons of two different calibers, he said.There were at least three suspects involved in a shootout at a crowded food festival near Seattle's Space Needle over the weekend, police said Monday. One of them was among those killed in the violence.In a document filed in juvenile court in Seattle, police said they believed there were at least three shooters: the 15-year-old, an acquaintance who died at the scene and "at least one other unknown suspect." Authorities had earlier said they believed there were two.RELATED STORY | Deadly shootout at Seattle food festival sparks gang violence investigationGhost guns are privately made firearms that lack serial numbers used to trace them and are often purchased without a background check.Law enforcement officials say ghost guns have increasingly been used in violent crimes across the U.S. ...read more read less