Where to report a unlicensed liquor store selling alcohol to underage minor?

Hello, I live in Central New Jersey and I notice a local liquor store which have been open for several years. I have seen the owner sell alcohol to teens and realize that they may be running a unlicensed liquor store. I want to know what can i do or who can I contact to help solve the problem in the neighborhood.|||The police.|||To your local Bureau of Alcohol Tobacco and Firearms.