Sanger police arrested a 17-year-old gang member on Friday after officers say they found a loaded firearm during a search tied to a felony warrant connected to a prior firearms charge, authorities said. Police said officers contacted the juvenile around 6 p.m. in the area of Church and Bethel avenues. During the encounter, officers served the warrant and conducted a search, locating a loaded firearm on the teen. Authorities said the juvenile had…